WIDEBAND DIGITAL LOCK-IN AMPLIFIER

LI 5655 / LI 5660
INSTRUCTION MANUAL(OPERATIONS)NF Corporation

DA00053267-005

WIDEBAND DIGITAL LOCK-IN AMPLIFIER

LI 5655 / LI 5660
INSTRUCTION MANUAL(OPERATIONS)Registered Trademarks
National Instruments and LabVIEW are registered trademarks of National Instruments
Corporation in the United States.
Other company names and product names used in this instruction manual may be trademarks orregistered trademarks of their respective companies.

Preface──── Preface ────Thank you for purchasing our "LI 5655 / LI 5660 WIDEBAND DIGITAL LOCK-IN
AMPLIFIER".
Before using this device, please first read "Safety Precautions" on the following pages to
use the instrument in a correct and safe manner.
■ Caution Symbols Used in This Manual
The following caution symbols are used in this manual. The instructions by these alert symbols shall becarefully obeyed to ensure equipment operator’s safety, and prevent damage to equipment.
！

WARNING

This contains information to avoid electric shock and other risks when handling theequipment that could result in the death or bodily injury of the operator.

！ CAUTION

This contains information to avoid risks when handling the equipment that could
result in minor or moderate injury of the operator or damage to property.

i

LI 5655 / LI 5660

Preface

The following instruction manuals are provided for LI 5655 / LI 5660.
LI 5655 / LI 5660 Instruction Manual (Operations)This manual describes basic items such as how to operate the LI 5655 / LI 5660 from the panel,specifications, and maintenance.

LI 5655 / LI 5660 Instruction Manual (Remote Control)
This manual describes how to remotely control the LI 5655 / LI 5660.

This manual (Operations) has the following chapters.
If using this equipment for the first time, start from Chapter 1.

1. Outline
This chapter provides an overview and describes the features, applications, functions, andsimple operation principles of this product.
2. Preparation before UseThis chapter describes important preparation before installation and operation.
3. Panel Operation List
This chapter shows the function and operating procedure of each panel screen part and thecontents of the display screens for initial values and measurement values. Read this to get an
overall understanding.
4. Basic Operations
This chapter describes the basic operation procedures when the LI 5655 / LI 5660 is used as anormal single-frequency, dual-phase lock-in amplifier. Please read this chapter while operating
the instrument.
5. Advanced Operations
This chapter describes the more advanced operations as a single-frequency, dual-phase lock-in
amplifier.
6. Dual Frequency Measurement
This chapter describes the operation procedure to perform measurements with two frequencies
simultaneously using two dual-phase sensitive detectors.
7. TroubleshootingThis chapter describes how to deal with error messages and trouble.
8. MaintenanceThis chapter describes storage, repacking, and transportation as well as how to test performance.
9. Specifications
This chapter describes the specifications (functions and performance).

ii

LI 5655 / LI 5660

Safety Precautions──── Safety Precautions ────To ensure safe use, be sure to observe the following warnings and cautions.
NF Corporation shall not be held liable for damages that arise from a failure to observe these warnings andcautions.
This product is a Class I device (with protective conductor terminal) that conforms to the IEC insulation
standards.
Be sure to observe the information in the instruction manual.
This instruction manual contains information for the safe operation and use of this product.
Be sure to read this information first before using this product.
All the warning items contained in this instruction manual are intended for preventing risks that may
lead to serious accidents. Ensure to obey them.



Be sure to perform grounding.
This product uses a line filter which may cause electric shock if the product is not grounded.
To prevent electrical shock accidents, connect the product to an earth ground so that ground resistanceis 100  or less.
This product is automatically grounded by connecting a 3-pin power plug to a power outlet with aprotective ground contact.

Check the power supply voltage.
This product operates on the power supply voltage specified in "2.3 Grounding and Connecting toPower Outlet" of this instruction manual.
Prior to connecting the power supply, check that the voltage of the power outlet matches the rated
power supply of the product.



Observe the rating of the fuse.
There is a risk of fire or other accident. Use a fuse with the rating specified in "2.3 Grounding andConnecting to Power Outlet" of this instruction manual.
Before replacing the fuse, be sure to disconnect the power cord from the outlet.



In case of suspected anomaly
If this product emits smoke, an abnormal smell, or abnormal noise, immediately stop use anddisconnect the power cord.
If such an abnormality occurs, prevent anyone from using this product until it has been repaired, andimmediately report the problem to NF Corporation or one of our representatives.

iii

LI 5655 / LI 5660

Safety Precautions



Do not use this product when gas is present.
An explosion or other such hazard may result.



Never remove the cover.
There are high voltage parts inside this product. Never remove the cover.
Even when the inside of this product needs to be inspected, do not touch the inside. All suchinspections are to be performed by service technicians designated by NF Corporation.



Do not modify this product.
Never modify the product. Modification to the product may pose a new risk. We may refuse the repairof a modified product at fault.



Do not expose the product to water.
Using the product while it is wet may cause electric shock or fire. If this product is exposed to water,
immediately disconnect the power cord and contact NF Corporation or one of our representatives.



If lightning occurs nearby, turn off the power switch and disconnect the power cord.
Lightning may cause electric shock, fire, or failure.

Safety-related symbols
The general definitions of the safety symbols used on the product main unit and in the instruction
manual are provided below.

！

Instruction manual reference symbolThis notifies the user of a potential hazard and indicates that the user must referto the instruction manual.
Electric shock danger symbolThis symbol indicates a location that presents a risk of electric shock under
specific conditions.

！ WARNING

Warning SymbolThis contains information to avoid risks when handling the equipment that
could result in the death or serious injury of the operator.

！ CAUTION

CautionThis contains information to avoid risks when handling the equipment that
could result in minor or moderate injury of the operator or damage to property.

Other symbols
Indicates the ON position of the power switch.
Indicates the OFF position of the power switch.
Indicates connected to the case.
Indicates that the outer contact of the connector is isolated from the enclosure.
However, indicates that the difference of the potential from the ground
potential is restricted to 42 Vpk or less for safety (this product is usedgrounded so the enclosure potential and ground potential are equal).

iv

LI 5655 / LI 5660

Safety Precautions

Electromagnetic compatibility
This product is a CISPR 11 Group 1 Class A compliant device. Do not use this product in other thanan industrial area. This product may cause electromagnetic interference with other devices if used in
an ordinary office or residence.



Request about disposal
To protect the environment, please note the following guidelines for disposal of this product.
a) This product does not contain batteries.
b) The LCD backlight of this product does not contain mercury.
c) Ask an industrial waste disposal contractor to dispose of this product.

v

LI 5655 / LI 5660

Table of ContentsPage

1． Outline ........................................................................................................1-1
1.1 Features ..................................................................................................................... 1-2
1.2 Applications................................................................................................................ 1-3
1.3 Operating Principle .................................................................................................... 1-8

2． Preparation Before Use ..............................................................................2-1
2.1 Checking Before Use ................................................................................................. 2-2
2.2 Installation .................................................................................................................. 2-4
2.3 Grounding and Connecting to Power Outlet............................................................ 2-10
2.4 Simplified Operation Check ..................................................................................... 2-13
2.5 Calibration ................................................................................................................ 2-14

3． Panel Operation List ...................................................................................3-1
3.1 Panel Part Names and Operations ............................................................................ 3-3
3.2 I/O Connector............................................................................................................. 3-6
3.3 Overview of the Measurement Screen .................................................................... 3-13
3.4 Overview of the Operation Screen .......................................................................... 3-18
3.5 Operation Tree ......................................................................................................... 3-21
3.6 Operation Screen Reference ................................................................................... 3-31
3.7 Initial Settings........................................................................................................... 3-62

4． Basic Operations.........................................................................................4-1
4.1 Display and Operation when Power Is Turned On .................................................... 4-3
4.2 Simple Operation Procedure for Using the Device for the First Time ....................... 4-4
4.3 Measurement Parameter Setting, Output, and Display............................................. 4-8
4.4 Reference Signal Setting and Connection .............................................................. 4-11
4.5 Input Connector Setting and Connection ................................................................ 4-15
4.6 Time Constant Filter Setting and Characteristics .................................................... 4-23
4.7 Sensitivity and Dynamic Reserve Setting................................................................ 4-28
4.8 Phase Adjustment .................................................................................................... 4-33

5． Advanced Operations .................................................................................5-1
5.1 Measured Value Offset and Expansion ..................................................................... 5-3
5.2 Line Frequency Noise Removal ................................................................................ 5-5
5.3 Harmonic Measurement (Harmonic, Subharmonic, Fractional Harmonic) ............... 5-6
5.4 External 10 MHz Synchronization ............................................................................. 5-7
5.5 Arithmetic Processing (Normalize and Ratio)............................................................ 5-8
5.6 Noise Density Measurement ................................................................................... 5-12vi

LI 5655 / LI 5660

Table of Contents

5.7 PSD Input Offset Adjustment ................................................................................... 5-15
5.8 DC Voltage Measurement (AUX IN) ........................................................................ 5-17
5.9 DC Voltage Output (AUX OUT) ............................................................................... 5-19
5.10 Supplying Power to the Preamplifier ....................................................................... 5-20
5.11 Setting Memory ........................................................................................................ 5-21
5.12 Other Functions ....................................................................................................... 5-23

6． Dual Frequency Measurement ....................................................................6-1
6.1 Overview of the Dual Frequency Measurement ........................................................ 6-3
6.2 Detection Mode Setting ............................................................................................. 6-7
6.3 Measurement Parameter Setting, Output, and Display(Dual frequency Measurement) ............................................................................... 6-8
6.4 Frequency Setting of the Internal Oscillator (Dual Frequency Measurement) ........ 6-10
6.5 Time Constant Filter Setting (Dual Frequency Measurement) ................................ 6-11
6.6 Sensitivity Setting (Dual Frequency Measurement) ................................................ 6-12
6.7 Phase Adjustment (Dual Frequency Measurement) ............................................... 6-12
6.8 Measured Value Offset and Expansion (Dual Frequency Measurement) ............... 6-13
6.9 Ratio Measurement (Dual Frequency Measurement) ............................................. 6-14

7． Troubleshooting ..........................................................................................7-1
7.1 Error Message ........................................................................................................... 7-2
7.2 Troubleshooting ......................................................................................................... 7-6
7.3 Q & A .......................................................................................................................... 7-7

8． Maintenance ...............................................................................................8-1
8.1 Preface....................................................................................................................... 8-2
8.2 Daily Maintenance ..................................................................................................... 8-3
8.3 Storage, Repacking, and Transportation ................................................................... 8-3
8.4 Version Confirmation ................................................................................................. 8-4
8.5 Main Function Confirmation ....................................................................................... 8-5
8.6 Performance Test ....................................................................................................... 8-6
8.7 Calibration ................................................................................................................ 8-28
8.8 Maintenance Information ......................................................................................... 8-29

9． Specification................................................................................................9-1
9.1 Measured signal system ............................................................................................ 9-2
9.2 Phase Sensitive Detector Section ............................................................................. 9-7
9.3 Reference Signal System ........................................................................................ 9-11
9.4 Arithmetic Processing .............................................................................................. 9-15
9.5 Measured Value Output and Display Section .......................................................... 9-17
9.6 Monitor Output ......................................................................................................... 9-18
9.7 Auxiliary Input (DC Voltage Measurement) ............................................................. 9-19vii

LI 5655 / LI 5660

Table of Contents

9.8 Auxiliary Output (DC Voltage Output) ...................................................................... 9-19
9.9 Automatic Setting Items ........................................................................................... 9-19
9.10 Data Memory ........................................................................................................... 9-20
9.11 Remote Control Interface ........................................................................................ 9-21
9.12 General Specifications ............................................................................................. 9-22
9.13 External Dimensions Diagram ................................................................................. 9-23

viii

LI 5655 / LI 5660

Table of Contents

Figures and Tables
Page
Figure 1-1 Basic Principle of a Lock-in Amplifier................................................................. 1-8
Figure 1-2 LI 5655 / LI 5660 Block Diagram ........................................................................ 1-9
Figure 2-1 Rack Mount Kit Assembly Drawing (JIS) ........................................................... 2-6
Figure 2-2 Rack Mount Kit Assembly Drawing (EIA) .......................................................... 2-7
Figure 2-3 Rack Mount Dimensions (JIS) ........................................................................... 2-8
Figure 2-4 Rack Mount Dimensions (EIA)........................................................................... 2-9
Figure 2-5 Power Voltage Selector Switch ........................................................................ 2-10
Figure 2-6 Fuse Replacement ........................................................................................... 2-12
Figure 3-1 Front Panel ........................................................................................................ 3-3
Figure 3-2 Rear Panel ......................................................................................................... 3-4
Figure 4-1 Noise Figure (Supplementary Values) ............................................................. 4-16
Figure 4-2 CMRR (Supplementary Values)....................................................................... 4-17
Figure 4-3 I Input Frequency Characteristics (Supplementary Values) ............................ 4-19
Figure 4-4 I Input Referred Noise Density (Supplementary Values) ................................. 4-19
Figure 5-1 Line Filter Characteristics .................................................................................. 5-5
Figure 5-2 10 MHz Synchronous System Example ............................................................ 5-7
Figure 5-3 Ratio Measurement Application Example (Dual Beam Method) ..................... 5-10
Figure 5-4 Noise Measurement and Bandwidth................................................................ 5-14
Figure 9-1 LI 5655 External Dimensions Diagram ............................................................. 9-23
Figure 9-2 LI 5660 External Dimensions Diagram ............................................................. 9-24
Figure 9-3 LI 5655 Panel Diagram ..................................................................................... 9-25
Figure 9-4 LI 5660 Panel Diagram ..................................................................................... 9-26

Table 2-1 Composition List .................................................................................................. 2-2
Table 3-1 Setting Items and Initial Values ....................................................................... 3-63
Table 7-1 In case of suspected anomaly ............................................................................. 7-6ix

LI 5655 / LI 5660

Table of Contents(Blank)x

LI 5655 / LI 5660

1． Outline

1.1 Features ................................................................................ 1-2
1.2 Applications ........................................................................... 1-3
1.3 Operating Principle ................................................................ 1-8
1.3.1 Basic Principle of a Lock-in Amplifier........................................ 1-8
1.3.2 Block Diagram .......................................................................... 1-9

1-1

LI 5655 / LI 5660

1.1 Features

1.1 Features
The "LI 5655 / LI 5660 WIDEBAND DIGITAL LOCK-IN AMPLIFIER" is a dual-phase, dual frequency
lock-in amplifier with a frequency range of 0.5 Hz to 11 MHz. (with the LI 5655, 0.5 Hz to 3 MHz)
It can be widely used to measure the magnitude and phase of a small AC signal buried in noise, taking
advantage of the following features.
For details on the basic functions and terms of a lock-in amplifier,  "1.3 Operating Principle"
 Wideband
A signal of up to 3 MHz of voltage input can be measured. With the LI 5660, up to 11 MHz can be usedby using a special input connector (HF) (there are some functional restrictions).
The -3 dB bandwidth for current input is 1 MHz (nominal value when signal source capacity +connection cable capacity = 150 pF).
 Variety of Reference Signals
In addition to a synchronous function with general external reference signals, internal oscillation signals,
and measured signals without a reference signal, a signal can be synchronized with the frequency
reference of other devices using an external 10 MHz (10 MHz IN connector).
 Variety of Detection Functions
In addition to general harmonic measurement, the following functions are provided.
a) Fractional Harmonic Measurement
In addition to the harmonic, a frequency of a submultiple of the fundamental wave (x 1 / 1 to 63 /63) can be measured.
b) Dual Frequency Simultaneous Measurement
Two sets of dual phase sensitive detectors enable two frequency components included in a single
input signal to be measured simultaneously. Two-component ratio arithmetic processing (RATIO)
and cascade-connection of detectors are also possible.
 Digital Processing Ensures High Stability and Superior Dynamic Reserve
Phase detection and subsequent processing are performed digitally. Output zero drift at high gains issmaller than the analog system, and up to 100 dB dynamic reserve can be obtained (measurement can be
performed with a noise 100 000 times larger than the sensitivity, namely the signal full scale).
 High-speed Smooth Output Response
The maximum update rate is approximately 1.5 M samples/s, and the amplitude resolution is 16 bits.
 High-speed Locking Even at Low Frequencies
It takes just about two cycles to lock on to the reference signal even at low frequencies. Furthermore, amoving average filter synchronized with the signal cycle obtains a high-speed response with a small
ripple.
 10 Vrms Signal Input (LI 5660 Only)
A signal of up to 10 Vrms can be measured (C connector). A large signal output of an external
preamplifier can also be input.
 Remote Control
USB, GPIB, RS-232, and LAN are available, which facilitate incorporation into automatic measurement
systems. The maximum transfer rate of measured values is 100 k samples/s (USB).
 Thin Design
The height is 88 mm (2U) so it can easily be mounted in a rack.
1-2

LI 5655 / LI 5660

1.2 Applications

1.2 Applications
The LI 5655 / LI 5660 can be used in the following fields, taking advantage of its features.


Scanning probe microscope signal detectionSpectroscopy (material science using Auger electron spectroscopy, photoacoustic
spectroscopy, Raman spectroscopy, etc.)Measurement of optical properties (intensity, absorption, scattering, transmission, etc.)

Optical application measurements (optical gyro, detection of distance, speed, vibration,
etc.)



Magnetic measurements (evaluation of magnetic materials, vibration-type magnetometer,
magnetic detection using SQUID)Hall coefficient measurement



Evaluation of various sensors (measurements of physical quantities detected by optical,
magnetic, and piezoelectric elements, chemical changes, etc.)Null detection with impedance bridge

Impedance measurements (minute impedance, minute capacity, chemical impedance)

Thermal diffusivity measurement of thin film materials■ Typical Application Examples of the Phase Sensitive Detector
The following measurements can be performed using the phase detection feature in order to detectspecific phase components.
a) Position Detection Using a Differential Transformer

SignalGood linearity bidirectional position detection
X OUT

Ordinary voltmeter
outputcan be performed using phase detection. This is

Signalalso suitable for position feedback control.
An ordinary voltmeter cannot identify the
Displacement

direction, and the linearity near the zero point
deteriorates due to mixing of noise or crosstalk.

Differential
transformer(before correction）
LIA output(after correction）

A lock-in amplifier provides good linearity and
it is easy to correct a zero-point error.

LIA: Lock-in amplifier

1-3

LI 5655 / LI 5660

1.2 Applications

Signalstrengthb) Spectral Characteristic Curve Peak Detection
If a minute "change" is superimposed on the

Phase
-/+

wavelength sweeping and the "change" of thesignal strength is measured using a lock-in
amplifier, the differential value of the characteristic

Signalcurve can be obtained. This value goes throughY OUTWave length

zero at the peak or bottom of the characteristic

Differential value

curve (a positive/negative inversion occurs), so it iseasy to obtain that position.
Since the deviation direction can be identified, it
can be used for automatic control to follow thepeak wavelength.

■ Application Examples Taking Advantage of the Features of the LI 5655 / LI 5660
The following measurements can be performed using a variety of functions of the LI 5655 / LI 5660.
a) Hall Coefficient Measurement (Difference Frequency Signal Measurement)
The hall voltage is proportional to the product of two signals (current and magnetic field), and its
frequency is the difference frequency (and sum) frequency of the two signals. Synchronizing an
external signal, which generates a current and magnetic field, with the LI 5655 / LI 5660 at an external
10 MHz allows measurement of the difference frequency signal of any two frequencies without having
to arrange an external reference signal (difference frequency).
To avoid the intermodulation in the LI 5655 / LI 5660, sufficiently suppress the original f 1 and f 2components included in the input.
If the original frequency is an integer
EXT OSC Large current(2 CH)（metal）
SampleLI 5655 / LI 5660

ratio, the difference frequency signal
can also be measured using the

f2

Hall
voltage

f1

f2 - f1

PSD
OUT

fractional

harmonic

measurement

function. Both can avoid a crosstalk
Strongmagnetic field

f2 - f1
INT
OSC

10MHz IN

interference

from

the

externalreference signal.

10MHz Standard frequency
f1 : f2 = p : q（integer ratio）

REF INf1

n/m

f2 - f1= f 1 × (q - p) / p= f1 × n / m

1-4

LI 5655 / LI 5660

1.2 Applicationsb) Measurement of Light Transmission and Absorption, and Suppression of Illuminant
Fluctuation
Using both the simultaneous dual-frequency measurement and fractional harmonic measurement
functions allows fluctuation corrections of light sources and other sources using the dual beam method(ratio measurement) with a single LI 5655 / LI 5660.
Applying negative feedback to the reference cell signal also stabilizes the strength of the light source.

f1 : f2 = n : m

Samplecell
f1

f1 & f2

I

LI 5655 / LI 5660
f1 & f2

Sensorf1

f2
Reference
cellLight chopperor
Optical modulator

a

n/m

RATIO
a/b

Light
sourceOUTb
REF INf2

f2
Dual frequency &Fractional harmonic measurement(Negative feedback)To avoid mutual interference, avoid two frequencies from being in a relationship of harmonic andsubharmonic. Modulation and detection are also possible by two arbitrary frequencies bysynchronizing with an external signal generator using the 10 MHz synchronization function.

1-5

LI 5655 / LI 5660

1.2 Applicationsc) Dual Demodulation
If the pump light and probe light are modulated at different frequencies or a sample is excited withtwo pump lights with different modulation frequencies, an amplitude modulation signal is obtained
from the sensor and information may be included in this envelope. The LI 5655 / LI 5660 can
demodulate an amplitude modulated signal and then detect the obtained envelope signal by internallycascade connecting the two detectors.
LI 5655 / LI 5660
DET2

Envelope f 1
Carrier

DET1

f2

X

X

R

+90°
INT OSCY

10MHz INA

SampleAmplitude

10MHz

f2 - f1

f 2 : CarrierPD

f2 + f1

f1
f2

θModulator

Ma

Pump
f1

Modulator

Mb

Probe

EXT OSC
f2

10MHz

Frequency

Envelope information can be obtained by detecting the amplitude modulation signal.

1-6

LI 5655 / LI 5660

1.2 Applicationsd) High Frequency Detector (for the LI 5660 Only)
Transient Absorption (TA) and Simulated Raman Scattering (SRS) use a laser light modulated at ahigh frequency (10 MHz or more) in order to avoid semiconductor laser noise and increase the speed.
When the HF connector and 10 MHz synchronization function are used, measurement can be
performed without receiving interference from an external reference signal. If the HF connector isused, install a band pass filter (BPF) or tuning amplifier at the front in order to reduce noise outside of
the measurement band (>11 MHz) of the LI 5660.
If the frequency is selected properly and a moving average filter (SYNC) is used, a high-speed
response can be obtained.
Ex)

Filter
Probe

EXT
OSC

f0

PSD

LPF

Input rate
= 25 M sample/s
Output rate
= 1.5625M sample/s

HF

PD

OM

SYNC:
Moving average

Tuned AmporBPF

f 0 = 9.375 MHz

OUT
f0

Sample
PD: PhotodiodeOM: Optical modulator

Pump

10MHz IN

10 MHz Standard Frequency

1-7

LI 5660INTOSCEx) Averaging= 48 points= 18 cycles of f 0
 1 / (520.8 kHz)
Response time 2μs

LI 5655 / LI 5660

1.3 Operating Principle

1.3 Operating Principle
1.3.1 Basic Principle of a Lock-in Amplifier
In general, noise is distributed over a wide range of frequencies. A lock-in amplifier is a device that uses thedifference of the frequencies to separate signal and noise and amplify the signal. It works as a narrow band
pass filter / tuning amplifier where the center frequency equivalently follows the signal.
The frequency of a signal including noise is first converted to a DC voltage using a Phase Sensitive
Detector (PSD). At this point, noise in the vicinity of the signal frequency is also converted to the vicinityof DC. Then, the noise and ripple caused by detection are removed using a low pass filter (LPF) to obtainthe DC component. When this is returned to the original frequency, the equivalent bandwidth is equal to theband pass filter (BPF) that is double the cutoff frequency (f c) of the LPF. Increasing the time constant(response time) and attenuation slope (number of steps) of the filter decreases the f c, so more noise can beremoved. After the noise is removed using the LPF, a signal can be amplified without being saturated by
the noise. AC gain before phase detection and DC gain after it are determined by the sensitivity anddynamic reserve (DR) settings. (DR = maximum allowable noise level / full-scale sensitivity)
A lock-in amplifier needs a reference signal (REF IN) as the reference of the frequency and phase.
The PSD is a multiplier of a measured signal and reference signal (both are a sine wave and the same
frequency). The amplitude of a reference signal applied to the PSD is constant, and the phase can be shifted.
The PSD output is dependent on the magnitude of the measured value (R) and the phase difference fromthe reference signal (θ).
A dual-phase lock-in amplifier is equipped with two PSDs, and works as a vector voltmeter that can obtain
two orthogonal components X and Y (in other words, R and θ) simultaneously. If the phase of the reference
signal applied to the PSD is adjusted so that Y is zero, and the magnitude of the signal is measured using X,
the influence of random noise can be reduced more than with measurement using the R output.

AC Amp

PSD

LPF

2
2
R X Y

DC Amp1
θ  tan ( Y X)

Y OUTSignal+Noise
f0

R sin θR
+90° Phase Shifter

Phase
shifterθ
X OUT
SIG INR cos θLPF
fC

± 180°sin(2πf 0t + θ) sin(2πf 0t)= (cos θ - cos(4πf 0t + θ) ) / 2

Amplitude

Equivalent

Phase Shifter

REF IN
f0

SIG IN
SignalX

DC + 2 f 0

Amplitudeθ

SignalvectorY

DC+ NoiseOUT

Saturation level

0
(DC)

Noise

BPF
2fC

f0
Signal2 f0
RippleFrequency conversion
AC Gain
SIG IN ×

LPF
DC Gain
Signal gain
Noise gain

(No LPF)
DR = DC Gain

Figure 1-1 Basic Principle of a Lock-in Amplifier

1-8

LI 5655 / LI 5660

1.3 Operating Principle

1.3.2 Block Diagram
The following shows a schematic block diagram of the LI 5655 / LI 5660 and describes the main functions.

1μA

1M / 100M

I

I-V

C
10V

A3

A2

A-B / AFLOAT / GND

THRU /
50 / 60Hz

Buf

Buf

Buf

A/D

HF-IN

C-IN
LINE NOTCH

A1

B

DC
CancelA4

Diff AMP

1V
A

A5

HF
1M 50Ω

LI 5660 only

I / V AC / DC

MONITOR
OUT

1V[SIGNAL INPUT CKT]ANTIALIASINGFILTER

THRU/
100 / 120Hz

AC GAIN(SENS, DR)

DC GAIN(SENS, DR)

REF 1

STANDARD
K

RATIO

D/A

LPF
PRIMARY
DETECTOR[ CALCULATE ]
NOISE

Buf

D/A

Buf

DATA
OUT 1
DATA
OUT 2
DATA
OUT 3
DATA
OUT 4

DET2
OUT

PSD 2

Buf

D/A

FORMAT+90 ﾟ

OFFSET EXPAND
X, Y
X, Y

NORMALIZETC, SLOPE,
SYNC
PSD 1 X, Y

D/A

Buf
±10V

CASC

DATA
to CPU / MEMORY

/
+90°

REF 2

SECONDARYDETECTORn/m

REF IN[ DETECTOR CKT ]FREQUENCY

REFERENCE
DETECTOR

PHASE

REF 1

PHASE
SHIFTER 1

PLL

10MHz IN

INT OSCSWITCHDUAL

OSC OUT
D/A

ATT

REF 2
PHASE
SHIFTER 2

REF OUTAMPTD[ REFERENCE CKT ]CONTROL, STATUS, DATA

AUX
IN 1

A/D

D/A

Buf

AUX
OUT 1

AUX
IN 2

A/D

D/A

Buf

AUX
OUT 2

TRIG IN
PREAMP±15V OUT
AC LINE

MAIN CPUPOWER
SUPPLYDC
POWER[ CONTROL CKT ]REMOTECONTROL

PANEL

Figure 1-2 LI 5655 / LI 5660 Block Diagram

1-9

LI 5655 / LI 5660

1.3 Operating Principlea) Signal Input Section (SIGNAL INPUT CKT)The signal input section has the following functions. (Only the LI 5660 is equipped with the C and HF
connectors)
Input connector selection (A, A-B, C, I, HF)
Input coupling selection (AC, DC)
Signal amplification (AC amplification)
Power line frequency noise removal (LINE NOTCH)
Anti-aliasing filter (ANTI-ALIASING FILTER)
Prevents noise outside of the band from aliasing into the signal band by means ofsampling.
If the HF connector is used, the filter must be installed at the front to suppress noise
outside of the measurement band, because the signal does not pass through theanti-aliasing filter.
b) Detector (DETECTOR CKT)Sampling
An input signal is converted to a 16-bit digital signal at a sampling rate of 25 M
samples/s. Although omitted in the figure, a dither signal (a sort of noise) for
distributing the quantization noise is added to increase the number of effective bits forthe narrow band signal.
Phase Sensitive Detection (PSD)
The frequency of a signal is converted to a DC voltage using a Phase Sensitive
Detector (PSD).
Information of the magnitude and phase of a signal are saved by detecting them using
two orthogonal phases. Phase sensitive detection is accomplished by multiplexing an
input signal and internal reference signal. Since a reference signal applied to the PSD
is a sine wave, there is no influence of the harmonic of an input signal, which becomesa problem when a simple square wave reference signal is used. A ripple doubling thesignal frequency occurs in the product of a measured signal and reference signal, andthe same ripple as with the signal frequency occurs in the product of an input DC
offset and reference signal, but they are removed by a time constant filter in the next
step. A lock-in amplifier only measures AC signals so it has the advantage that it is
not affected by the thermal electromotive force (DC).
Time Constant Filter (TC, SLOPE, SYNC)
The time constant filter removes the noise and ripple caused by detection. Normally,
the time constant filter consists of a 1’st order low pass filter (LPF) and 1 to 4 steps(attenuation slope 6 / 12 / 18 / 24 dB/oct equivalent) that are cascade connected.
Increasing the time constant (TC) and attenuation slope (SLOPE) narrows the
bandwidth to remove more noise, but slows the output response. Switching the time
constant filter operation to the synchronous filter (SYNC, moving average of theinteger cycle) significantly reduces the ripple in the detection output, so it is easy toobtain a high-speed response by applying a small time constant value.

1-10

LI 5655 / LI 5660

1.3 Operating Principle

Amplification (DC GAIN)
When noise is removed, a signal can be amplified without being saturated by the noise.
AC gain before phase detection and DC gain after it are determined by the sensitivity
and dynamic reserve. The phase sensitive detector, time constant filter, and DC signal
amplifier use digital operations, so there is no limit to the dynamic reserve caused by
DC drift, which becomes a problem in the analog method.
Dual Frequency Simultaneous Measurement (PSD1, PSD2)
The LI 5655 / LI 5660 is equipped with two dual-phase Primary and Secondary PSDs.
Measurements can be performed simultaneously at two frequencies. The two detectors
can also be used by cascade connecting them.
c) Calculate Section (CALCULATE / FORMAT)
Measured values X and Y of the lock-in amplifier are the RMS values of orthogonal phase components.
R calculated from X and Y is the RMS value of a signal (sine wave).
The output offset adjustment (OFFSET), expansion (EXPAND), normalize arithmetic processing (%, dB,etc.), and ratio arithemetic processing (RATIO) can be performed as needed.
d) Reference Signal System (REFERENCE CKT)An internal reference signal (sine wave at a constant amplitude) used by the PSD is supplied by theinternal oscillator.
External Reference Signal
In principle, a lock-in amplifier performs the measurements using an externalreference signal (REF IN) as the reference of the frequency and phase. If the reference
signal source is an external reference signal, the internal oscillator generates a sine
wave synchronized with the external reference signal (the frequency and phase match)using a Phase Locked Loop (PLL).
Internal Oscillator
If the reference signal source is internal (INT OSC), the internal oscillator oscillates asignal at a frequency specified by a numerical value. The internal oscillator uses a
direct digital synthesis method so the frequency is stabilized immediately after it isset.
The signal of the internal oscillator is output as a sine wave (OSC OUT) or TTL-levelsquare wave (REF OUT). If the amplitude of OSC OUT is set to zero, interference(crosstalk) from the reference signal to the measured signal can be reduced, which isoften a problem in particular at high frequencies.
The internal oscillator has a function to generate a harmonic (harmonic, subharmonic,
and fractional harmonic) signal.
Two reference signals

aregenerated for the dual

frequency simultaneous

measurement. A fundamental wave and harmonic wave or the primary frequency andan arbitrary secondary frequency independent from it (specified by a numerical value)
can be used.

1-11

LI 5655 / LI 5660

1.3 Operating Principle

Synchronization with the Measured Signal
If the measured signal is specified for the reference signal source (SIGNAL), theinternal oscillator is controlled so that the measured phase value is set to zero (thefrequency and phase match).
External 10 MHz Synchronization
If a reference frequency for frequency synthesis is applied to (10MHz IN) from anexternal source, the internal oscillator generates a reference signal synchronized withthat reference frequency. Therefore, measurement can be performed without applying
an external reference signal (REF IN). Not only the signal frequency but also the signal
sampling rate, output update rate, and the rate for recording to the data memory by
the internal timer are also synchronized with the external 10 MHz.

1-12

LI 5655 / LI 5660

2． Preparation Before Use

2.1 Checking Before Use ............................................................ 2-2
2.2 Installation ............................................................................. 2-4
2.2.1 General Precautions for Installation ......................................... 2-4
2.2.2 Installation Conditions .............................................................. 2-4
2.2.3 Rack Mounting ......................................................................... 2-5

2.3 Grounding and Connecting to Power Outlet .......................2-10
2.4 Simplified Operation Check ................................................2-13
2.5 Calibration ...........................................................................2-14

2-1

LI 5655 / LI 5660

2.1 Checking Before Use

2.1 Checking Before Use■ Safety CheckTo ensure the safety, refer to "Safety Precautions" at the beginning of this instruction manual before
using the LI 5655 / LI 5660.
Furthermore, before connecting to the power supply, read "2.3 Grounding and Connecting to Power
Outlet" to ensure the safety.
■ Unpacking
Check that the device has not been damaged during transport.
After unpacking, refer to "Table 2-1 Composition List" to check the contents.
Table 2-1 Composition List
LI 5655 or LI 5660 ···························································· 1
Accessories
Instruction Manual (Operations)········································· 1
CD-ROM (Contents ☞ Next page) ···································· 1Power cord set (3-pole/2 m) ············································ 1
Fuse (time lag, φ5.2×20 mm) ··········································· 1
Protective cap (for current input connector) ·························· 1！ WARNING

There are high voltage parts inside this device. Never remove the cover.
No one except trained service technicians who have knowledge of hazard prevention
is authorized to check the inside of this device.

2-2

LI 5655 / LI 5660

2.1 Checking Before Use■ Contents of the Supplied CD-ROM


LI 5655 / LI 5660 Instruction Manual (Operations)This manual (in PDF format).



LI 5655 / LI 5660 Instruction Manual (Remote Control)
Describes how to remotely control the LI 5655 / LI 5660 (in PDF format).



IVI (Interchangeable Virtual Instruments) driver
Driver for handling the main commands and queries in the LI 5655 / LI 5660, which can be used invarious programming languages. In LabVIEW, the IVI driver can be imported and converted to ".vi"or ".llb".

Sample Programs
Show examples of controlling the LI 5655 / LI 5660 using programming languages such as C# and
VB.NET and various interfaces.
The above is just an outline. For details, refer to the instruction manual on the CD-ROM.

2-3

LI 5655 / LI 5660

2.2 Installation

2.2 Installation
2.2.1 General Precautions for Installation！ CAUTION

Observe the following points. Otherwise, the LI 5655 / LI 5660 may be damaged.
● The LI 5655 / LI 5660 uses a forced air cooling system using a fan.
Do not block the rear panel which has an air exhaust vent and both sides whichhave air intake ports.
● Do not install the LI 5655 / LI 5660 on its back or side. There is a risk of it fallingover.
Install it so that all of the four feet on the bottom sit on the flat surface of a table,
etc.

2.2.2 Installation Conditions● Install this product in a place that satisfies the following temperature and humidity conditions.
Operation: 0 to +40℃ , 5 to 85 %RH (Absolute humidity 1 to 25 g/m3, non-condensing)
Storage: -10 to +50℃ , 5 to 95 %RH (Absolute humidity 1 to 29 g/m3, non-condensing)● Install the device at an altitude below 2,000 m.
● Avoid use in the environment of a strong radio frequency magnetic field where themeasured values may fluctuate temporarily.
！ CAUTION

Avoid installation in the following locations.
● Where there is flammable gas
There is a risk of explosion. Never install or use it in such a location.
● Outdoors, where exposed to direct sunlight, or near fire or a heat source
The performance may not be satisfied, or a failure may occur.
● Where there are corrosive gases and vapors, a lot of dust and particles, salty air
and oily smoke, and metal powder, etc.
Corrosion or a failure may occur.
● Where there is a lot of vibration
Malfunction or a failure may occur.
● Near an electromagnetic field source, high-voltage equipment, power line, or pulse
noise source
Malfunction or a failure may occur.
Install the LI 5655 / LI 5660 and parts that may cause noise such as power cables of other equipment awayfrom the signal cable. If they are installed close to each other, a malfunction or measurement error may
occur.
To ensure correct measurement, warm up the device for at least 30 minutes before use.

2-4

LI 5655 / LI 5660

2.2 Installation

2.2.3 Rack Mounting
The LI 5655 / LI 5660 can be mounted in a 19-inch IEC rack, EIA standard rack, or JIS standard rack byattaching the rack mount kit (optional). Rack mount kits for Milli rack (JIS) and Inch rack (EIA) areavailable.
First, attach the rack mount kit as shown in Figure 2-1 Rack Mount Assembly Drawing (JIS) and
Figure 2-2 Rack Mount Assembly Drawing (EIA) , and then mount the device to a rack.

！ WARNING

When mounting to a rack, be sure to mount rack rails, etc. to support the LI 5655 / LI
5660. Otherwise, a fall may cause injury, or the LI 5655 / LI 5660 may be damaged.

！ CAUTION● Provide the rack with ventilation holes or a cooling fan for cooling.
● The LI 5655 / LI 5660 has an air intake port on both sides.
Provide clearance of at least 20 mm from the wall, etc. at the sides● There is an air exhaust vent on the rear panel.
Provide clearance of at least 50 mm panel from the wall, etc. at the rear
If the ambient temperature exceeds the specified limit, or air intake or
exhaust is blocked, the LI 5655 / LI 5660 may be damaged.

2-5

LI 5655 / LI 5660

2.2 Installation

Figure 2-1 Rack Mount Kit Assembly Drawing (JIS)2-6

LI 5655 / LI 5660

2.2 Installation

Figure 2-2 Rack Mount Kit Assembly Drawing (EIA)

2-7

LI 5655 / LI 5660

CAUTION
When storing in a rack, do not secure the units using only a rack mount adapter.
Always secure the units using L-shaped brackets or a shelf.

2.2 Installation

Figure 2-3 Rack Mount Dimensions (JIS)2-8

LI 5655 / LI 5660

CAUTION
When storing in a rack, do not secure the units using only a rack mount adapter.
Always secure the units using L-shaped brackets or a shelf.

2.2 Installation

Figure 2-4 Rack Mount Dimensions (EIA)

2-9

LI 5655 / LI 5660

2.3 Grounding and Connecting to Power Outlet

2.3 Grounding and Connecting to Power Outlet● Be sure to perform grounding.
！ WARNING

The LI 5655 / LI 5660 uses a line filter, which may cause electric shock if the device is
not grounded.
To prevent electrical shock, connect it to an earth ground so that ground resistance is
100 Ω or less.
The LI 5655 / LI 5660 is automatically grounded by connecting a 3-pin power plug to a 3-pin power outlet
with a protective ground contact.

■ The following shows the power supply conditions for this product.
Voltage range:100 V AC ±10% / 120 V AC ±10% / 230 V AC +10%, -14%
however, 250 V or lessFrequency range:50 Hz / 60 Hz ±2 Hz

Overvoltage category:Ⅱ

The maximum power consumption is 75 VA.
This product has a power supply voltage selector switch on therear panel. Check that the voltage of the outlet matches thevoltage set with the power supply voltage selector switch.
To change the power supply voltage, disconnect the power cord
and then turn the selector switch with a small flat-headscrewdriver slowly until you hear a click so that the key points to
Figure 2-5 Power Voltage

the setting voltage.

Selector Switch！ CAUTION
Set the power supply voltage selector switch to the position where it clicks to preventthe switch from being in a half-way position.
Check the power supply voltage selector switch setting and then connect the productto the power outlet.

2-10

LI 5655 / LI 5660

2.3 Grounding and Connecting to Power Outlet■ Perform the following steps to connect to the power outlet.
1) Check that the power outlet voltage to be connected is within the voltage range of this product.
2) Turn off the power switch of this product.
3) Connect the power cord to the power inlet on the rear panel of this product.
4) Insert the plug of the power cord into the power outlet with a protective ground contact.

！ CAUTION

Note that the supplied power cord set is specifically for use with the LI 5655 / LI 5660.
Do not use it for any other product or purpose.
Be sure to use the supplied power cord set to connect the product to the power outlet.
When turning the power off and then back on, wait at least 5 seconds before turning the power back on.

■ The power cord can be used to disconnect the LI 5655 / LI 5660 from the AC power outlet incase of an emergency.
！ WARNING

To ensure that the power cord can be disconnected from the power inlet on the LI
5655 / LI 5660, allow sufficient space around the inlet. Furthermore, to ensure that thepower plug can be disconnected from the outlet, use an outlet in an easily accessible
location and allow sufficient space around the outlet.
If you notice smoke or a strange odor or sound being emitted from the device,promptly disconnect the power cord, and do not use it until a repair is completed.

2-11

LI 5655 / LI 5660

2.3 Grounding and Connecting to Power Outlet■ Observe the rating of the fuse.
The following shows the rating of the fuse of the LI 5655 / LI 5660.
Power supply voltage 100 V / 120 V : Rated current 1.0 A, rated voltage 250 V
Power supply voltage 230 V: Rated current 0.5 A, rated voltage 250 V

Other characteristics
Electrical characteristic: Time lag

Dimensions: φ5.2 x 20 mm

To replace the fuse, disconnect the power cord, and then turn the fuseholder on the rear panel left with a flat-blade screwdriver and pull it out.
Replace the old fuse with a new one, insert the fuse holder, and turn it
right with a screwdriver to lock it.

Figure 2-6 Fuse
Replacement！ WARNING

Before connecting to the power supply, check that the power supply voltage selector
switch setting and the rating of the fuse match the power supply.
To change the power supply voltage selector switch setting and replace the fuse, besure to disconnect the power cord from the power inlet on the LI 5655 / LI 5660 or theoutlet.
Otherwise, the LI 5655 / LI 5660 may be damaged, or electric shock or fire may occur.

！ WARNING

There are high voltage parts inside this device. Never remove the cover.

2-12

LI 5655 / LI 5660

2.4 Simplified Operation Check

2.4 Simplified Operation Check
It is recommended to perform an operation check with the following procedure after you purchase theLI 5655 / LI 5660 or you have not used it for an extended period of time. (Prepare an oscillator and two
1-m BNC cables.)
1. Connect to the power supply and then turn on the power switch.
Wait until the startup screen disappears and the measurement screen appears.
For details on the startup,  "4.1.2 Startup Screen and Operation on Startup"
2. Reset the settings.
Press the __UTIL__ key, the [_ RESET> _] soft key, and the [_ Exec _] soft key.
3. Select the internal oscillator (INT OSC) for the reference signal source.
Press the REF _ key and the [_ SOURCE _] soft key.
Select INT OSC using the up/down keys or MODIFY knob.
4. Connect the OSC OUT connector and the SIGNAL INPUT A connector with a BNC cable.
5. Check that measurement can be performed correctly.
Change the output amplitude of the internal oscillator and check that the amplitude setting and themeasured value (R: magnitude of the signal) is almost the same.
Press the _ REF _ key and the [_ OSC SET> _] soft key, and then press the [ _FREQ> _] soft key tochange the frequency, or press the [_ AMPTD> _] soft key to change the amplitude.
6. Select the external reference signal (REF IN) for the reference signal source.
Press the _ REF _ key and the [_ SOURCE _] soft key.
Select REF IN using the up/down keys or MODIFY knob.
Press the [_ EDGE_ ] soft key and operate the up/down keys or MODIFY knob to select SIN (Rise +)or TTL-level square wave (Rise + / Fall -).
7. Prepare another oscillator (NF Corporation's Multifunction Generator WF1947, etc.) and configure
the following settings.
Waveform: Sine wave (SYNC OUT: TTL level, Duty: 50% square wave)
Oscillation mode: Continuous oscillation
Frequency: 1 kHz (change it within the range to be checked)
Amplitude: 1 Vrms (change it within the range to be checked)
8. Connect the output signal of the oscillator to the LI 5655 / LI 5660.
Oscillator synchronous signal (SYNC OUT) →LI 5655 / LI 5660 REF IN connector
Oscillator primary output (FUNC OUT) →LI 5655 / LI 5660 A connector
9. Check the synchronization function for the external reference signal.
When the signal is synchronized, the UNLOCK icon on the measurement screen disappears and thesame frequency as the external oscillator is displayed. Change the frequency and amplitude of theexternal oscillator and check that measurement can be performed correctly.
The simplified operation check is now complete.
It is recommended to reset the settings.

2-13

LI 5655 / LI 5660

2.5 Calibration

2.5 Calibration
Perform the performance test described in "8.6 Performance Test" at least once every year for the
LI 5655 / LI 5660, which may vary depending on the operating environment and frequency. Furthermore, it
is recommended to perform the performance test before using the device for important measurements andtests.
If the performance test results do not satisfy the specifications, NF Corporation will perform adjustment orcalibration to restore the original performance. If calibration or adjustment is required, contact NF
Corporation or one of our representatives. Charges apply for calibration and adjustment services.

2-14

LI 5655 / LI 5660

3． Panel Operation List
3.1 Panel Part Names and Operations ....................................... 3-3
3.1.1 Front Panel ............................................................................... 3-3
3.1.2 Rear Panel ............................................................................... 3-4

3.2 I/O Connector ........................................................................ 3-6
3.2.1 Signal Input Connector ............................................................. 3-7
3.2.2 Reference Signal Input Connector ........................................... 3-9
3.2.3 Analog Output ........................................................................ 3-10
3.2.4 Auxiliary I/O Connector .......................................................... 3-11
3.2.5 Other I/O Connector ............................................................... 3-12

3.3 Overview of the Measurement Screen ............................... 3-13
3.3.1 Types and Switching between Measurement Screens ........... 3-13
3.3.2 Measurement Screen ............................................................. 3-13
3.3.3 Details of the Measurement Screen ....................................... 3-15
3.3.4 Operations in the Measurement Screen ................................. 3-17

3.4 Overview of the Operation Screen ......................................3-18
3.4.1 Operation Keys and MODIFY Knob ....................................... 3-18
3.4.2 Operation Screen Configuration ............................................. 3-20

3.5 Operation Tree ....................................................................3-21
3.5.1 Operation Tree in the Measurement Screen........................... 3-21
3.5.2 Operation Tree in the Measurement Screen (SINGLE) .......... 3-22
3.5.3 Operation Tree in the Operation Screen (DUAL1) .................. 3-27
3.5.4 Operation Tree in the Operation Screen(DUAL2/CASCADE) ............................................................... 3-30

3.6 Operation Screen Reference ..............................................3-31
3.6.1

AUTO

: {Auto Setting Screen} .......................................... 3-32

3.6.2

DATA

: {Output Signal Setting Screen} ......................... 3-34

3.6.3

SENS

: {Sensitivity Setting Screen} ................................. 3-42

3.6.4

TC

3.6.5

SIG

3.6.6

PHASE

: {Phase Adjustment Screen}........................... 3-47

3.6.7

REF

: {Reference Signal Setting Screen} ..................... 3-48

3.6.8

AUX

: {Auxiliary I/O Setting Screen} ................................ 3-53

3.6.9

UTIL

: {Utility Screen}....................................................... 3-55

: {Time Constant Filter Setting Screen} ...................... 3-43
: {Input Signal Selection Screen} ........................... 3-45

3.7 Initial Settings ......................................................................3-63

3-1

LI 5655 / LI 5660

2.5 Calibration

This chapter describes the panel part names, operating system, and basic information common to various
operations.
Before reading Chapter 4 and onwards, please first read sections 3.1, 3.3, and 3.4.
If you wish to view the overall picture of the operating system or if you wish to know to which operation
screen a particular operation object is assigned, please see "3.5 Operation Tree."
For operations that are not described in detail in Chapter 4 and onwards, please see "3.6 Operation
Screen Reference."

3-2

LI 5655 / LI 5660

3.1 Panel Part Names and Operations

3.1 Panel Part Names and Operations
This section provides an overview of the part names, functions, and operations of the front and rear panels.

3.1.1 Front Panel*1: Only the LI 5660 is equipped with C and HF.
Display Panel4.3" WQVGA (480×272 dots) color LCD

Measurement Screen
The SCRN key allows you to switch sequentially between thefollowing screens.
Standard Displays the measured values and main settings in awell-balanced manner.
Expanded Displays the expanded measured values and bar graphs.
DetailDisplays the measured values and advanced settings.
The following keys allow you to perform simple operations.
Simple operation keys: Select the detector, parameter, etc.
Up/Down keys: Sensitivity
Left/Right cursor keys: Time constantOperation Screen
This is selected using the operation screen selection key.
The operation screen title, the setting values to be operated, thesetting range, etc. are displayed in the lower part.
The soft key title is displayed at the right end.
The digit of the value is selected using the left/right cursor keys andthe value is changed using the MODIFY knob or up/down keys.
The set value can be cleared using the _ CLR _ key.

CLR / LOCAL Key
This is used to clear the set value.
If the state is remote, it returns the state to local
operation (secondary function)
Hold down the key for 2 seconds to activate thefollowing tertiary functions.
・Disable the panel operation
・Turn off the display and lamp
・Cancel both of the above
REMOTE: Remote lamp
This is lit in the remote state.
KEY LOCK: Key lock lamp
This is lit when the panel operation is disabled.

Soft Key / Simple Operation Key
Works as a soft key in the operation screen and as asimple operation key in the measurement screen.
Operation Screen Selection Keys

MODIFY Knob
Up/Down Keys
Left/Right cursor Keys
These are used to set or select the parameter.

Signal Input Connectors
A Voltage (single-ended,1 V, Zin 10 MΩ)A-B Voltage (differential, 1 V, Zin 10 MΩ)
1
C Voltage (10 V, Zin 1 MΩ) *I
Current (I-V conversion gain 1M｜100M V/A)1
HF Voltage (10 kHz to 11 MHz, 1 V, Zin 1M｜50 Ω) *AC｜DC coupling can be selected for A｜A-B｜I.
FLOAT｜GND can be selected for an outer contact.

Reference Signal System
REF IN

External reference signal input
connector
1
0.5 Hz to 3 MHz (to 11 MHz at HF) *0.3 to 10 Vp-p or TTL
OSC OUT Internal oscillator output connector
0.5 Hz to 3 MHz, 0 to 1 Vrms, sine wave

Monitor Output Connector

DATA1/DATA2 Output Connectors
Analog output of measured values

PSD input signal.

POWER Switch

Figure 3-1 Front Panel

3-3

LI 5655 / LI 5660

3.1 Panel Part Names and Operations

3.1.2 Rear Panel
Reference Signal Output Connector

DATA3 and DATA4 Output

Outputs a square wave signal synchronized with theinternal reference signal.

Connector

Certification Label

Analog output of measured values

Power Connector
for Preamplifier

Power Voltage Selector Switch
Adjust to the power voltage before connecting
the power cord. Stop the selector at theposition where it clicks.

Cooling Fan Exhaust Port
Provide a space of at least
50 mm around this to ensure theexhaust is not blocked.

Fuse
Be sure to use the fusespecified for each power
voltage.

AUX IN 1 and 2
Auxiliary Input
Connector (DC)Supplies power to theexternal preamplifier.

AUX OUT 1 and 2
Auxiliary Output
Connectors (DC)Signal GroundTerminal
Do not use this as aprotective ground terminal.

RS-232Connector

LAN
Connector

Nomenclature
plate

GPIB
Connector

USB
Connector

Power Inlet
The center pins are for the protective
ground terminal
Be .sure to perform grounding.

Connectors for remote control

10 MHz Input Connector

External Trigger Input Connector

To synchronize the frequency of anotherdevice with that of the internal oscillator, apply
the same 10 MHz reference frequency to both.

Applies a trigger signal for recording themeasured value to the internal data memory.

Figure 3-2 Rear Panel
For details, refer to the description of the operations in Chapter 4 and onwards, as well as"9. Specifications."
For remote control, refer to "LI 5655 / LI 5660 Instruction Manual (Remote Control)" on the supplied CD
ROM.

3-4

LI 5655 / LI 5660

3.1 Panel Part Names and Operations

 Notation of the Screens and Keys in this Instruction Manual{Screen Names}
These are the names of screens displayed on the display panel. Screens are classified
into the following two types.
Measurement Screens {Standard｜Expanded｜Details}
Displays the main measured values and settings.
Operation Screens
Displays the following.
・ Main measured values and settings
・ Names and values of parameters to be operated and comments such as the setting range
・ Soft key functions_Hard Key Title_
Indicates a key with this name or symbol printed on the key top.
A cursor key indicates the direction by its shape and the title is not printed on it.
_Hard Key Title/ Secondary Function Name

Indicates a key that has the main function printed on the key top and a secondaryfunction printed near it. When the secondary function is executed in this instruction
manual, a notation with "/ secondary function name" added to the key is used. If themain function is executed, "/ secondary function name" is not added.
[_Soft Key Title_]
Indicates a soft key that has this function.
A hard key
refers to a key that is a physical entity with one or several functions.
With regard to a hard key with multiple functions, a secondary function may be enabledaccording to the situation.
A soft key
refers to a key, whose function changes depending on the situation.
The function displayed on the right end of the screen on the display panel is enabled in theoperation screen.
The soft key works as a simple operation key in the measurement screen, and the secondaryfunction indicated directly above the key is enabled.
A secondary functionrefers to a function not indicated on the key top, but near the key (above or under it).

3-5

LI 5655 / LI 5660

3.2 I/O Connector

3.2 I/O Connector！ WARNING

To prevent electric shock, ensure that the auxiliary input connector (AUX IN) of BNC
isolated from the enclosure and external 10 MHz synchronous connecor (10 MHz IN)
do not apply a voltage exceeding ±42 Vpk (DC ＋ AC peak) between the BNC
connector (center contact and ground) and the enclosure.
Likewise, to prevent electric shock, do not apply a voltage exceeding ±42 Vpk (DC＋AC peak) between the auxiliary input connector (AUX IN) and external 10 MHz
synchronous connector (10MHz IN).
If this voltage is exceeded, the internal voltage limiting element works to suppress thevoltage, but if the applied voltage is large, this product may be damaged.

！ CAUTION

Do not apply a voltage exceeding the maximum input voltage range to the input
connector. This product may be damaged.

！ CAUTION
Do not apply a voltage to the output connector from outside. This product may bedamaged.

3-6

LI 5655 / LI 5660

3.2 I/O Connector

3.2.1 Signal Input Connector*1: Only the LI 5660 is equipped with C and HF.
1) Signal Ground1

1

The signal ground for the signal input connectors (the following A, B, C * , HF * , and I connectors)
is isolated from the enclosure in a range of ±1 V.
Floating voltage (allowable voltage to ground) : ±1 Vpeak (DC＋AC)
Impedance to enclosure when floating: 10 kΩ (nominal value)

When grounded: 11 Ω (nominal value)
SwitchGround11 

Float 10 k

Signal ground

Enclosure±1 V pk

The ground impedance between the signal ground and enclosure can be switched between float andground. If a voltage exceeding ±1 V is applied, this isolation cannot be maintained.
！ CAUTION

42 Vpeak (DC+AC) cannot be applied between the signal ground and enclosure.
If a voltage exceeding 1.0 V is applied, a large current flows and damages the internal
circuit.

2) Voltage Measurement Input Connectors (A and B)
The following shows the voltage measurement connectors A and B.
Input impedance: 10 MΩ (nominal value), 50 pF in parallel(supplementary value)
Maximum input voltage (linear operating range): ±3 V (each connector voltage and differential
voltage in DC coupling)
Non-destructive maximum input voltage AC coupling : Sine wave 10 Vrms, ±42 V DC
DC coupling: ±14 V
Protective relay

AC / DC

+3V
+

0.15u

10M

A,B
-3V

！ CAUTION

If the signal significantly exceeds the maximum input voltage range, the input connector
may temporarily be separated from the inside for protection.

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LI 5655 / LI 5660

3.2 I/O Connector

13) Voltage Measurement Input Connector * (C)Input impedance: 1 MΩ (nominal value), 50 pF in parallel(supplementary value): ±30 V: ±42 V

Maximum input voltage (linear operating range)
Non-destructive maximum input voltage
+3V
C
1MΩ →

+
Attenuator

–

-3V

DC
Cancel14) Voltage Measurement Input Connector * (HF)
Input impedance: 1 MΩ (nominal value), 50 pF in parallel(supplementary value)｜50 Ω (nominal value): ±3 V: ±5 V

Maximum input voltage (linear operating range)
Non-destructive maximum input voltage
+3V
1000p

+

1M

50 / 1M

50

HF
-3V

5) Current Measurement Input Connector (I)Input impedance: 1 kΩ (conversion gain 1 M,
supplementary value)
100 kΩ (conversion gain 100 M,
supplementary value): ±3 μA (conversion gain 1 M, DC coupling): ±10 mA

Maximum input current (linear operating range)
Non-destructive maximum input current
100
I
–
+

！ CAUTION
If a current of ±10 mA or more flows, the internal circuit will be damaged. Attach the supplied
protective cap if the input current will not be used.

3-8

LI 5655 / LI 5660

3.2 I/O Connector

3.2.2 Reference Signal Input Connector
1) Reference Signal Input (REF IN)
If the EDGE setting is changed for the reference signal input connector, the internal circuit is alsochanged.
: 1 MΩ (nominal value), 100 pF in parallel(supplementary value): 0.3 V to 20 Vp-p
: 0 to 5 V (Low 0.8 V or less, High 2.6 V or more): ±15 V

Input impedance
Input voltage range, SINE
TTL
Non-destructive maximum input voltage
+15V

+3.3V

1.15M

1.5u
REF INREF IN

+
11k

1M

10M

+
10k
-15V
For SINE

For TTL

2) Sine Wave Output (OSC OUT)
A sine wave synchronized with the internal oscillator is output from the OSC OUT connector. If thesynchronous source is the external reference signal (REF IN), the output is synchronized with theexternal reference signal source.
Output voltage range
Maximum output current
Output impedance: 0.00 mVrms to 1.000 Vrms
: ±15 mA
: 50 Ω (nominal value)+5V

Attenuator

+5V
25

25

OSC OUT-5V-5V
Sine wave output

If the frequency is 3.2 MHz or more, the output is 0 Vrms regardless of the setting.
3) Square Wave Output (REF OUT)
A logic signal synchronized with OSC OUT is output.
Signal level:TTL (0 to 3.3 V, nominal value)
Maximum output current:±8 mA+5V
75
REF OUT

150

CMOS
LOGIC

Square wave output

If the frequency is 3.2 MHz or more, the output level is fixed to HIGH or LOW.

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LI 5655 / LI 5660

3.2 I/O Connector！ CAUTION

Do not apply a voltage exceeding the maxmum input voltage range to REF IN.
There is a limit of output current at OSC OUT
Ensure that the load to the REF OUT ground or +3.3 V is 500 Ω or more.

3.2.3 Analog Output
1) Measured Value Output (DATA OUT)
The following shows the DATA OUT1 and 2 on the front panel and DATA OUT3 and 4 on the rear
panel.
A voltage in proportion to the measurement display values (R, X, Y, etc.) is output.
For details,  "4.3 Measurement Parameter Setting, Output, and Display."
Output voltage range: ±12 V (with no load)

Maximum output current: ±10 mA

Output impedance: 470 Ω (nominal value)

+15V

+15V
470
DATA OUT
-15V

-15V

2) Monitor Output (MONITOR OUT)
Input signal to the phase sensitive detector.
For details,  "4.7.3 Signal Over-level Display and Monitor Output."
Maximum output voltage: ±3 V (with no load)

Maximum output current: ±20 mA

Output impedance: 50 Ω (nominal value)

+5V

+5V
25

25

MONITOR OUT
-5V
-5V

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LI 5655 / LI 5660

3.2 I/O Connector

3.2.4 Auxiliary I/O Connector
1) Auxiliary Input (AUX IN1 and AUX IN2)
AUX IN1 is used for ratio measurement.
For details,  "5.8 DC Voltage Measurement (AUX IN)"
: 1 MΩ (nominal value), 50 pF in parallel (supplementary value)

Input impedance

If the signal ground is equal to the enclosure potential
Maximum input voltage (linear operating range): ±12 V
Non-destructive maximum input voltage: ±42 Vpeak (DC+AC)
1M

AUX IN1
AUX IN2

42 Vpk（DC+AC）—+

1M±42 Vpk (DC+AC)

2) Auxiliary Output (AUX OUT1 and AUX OUT2)
For details,  "5.9 DC Voltage Output (AUX OUT)."
Output voltage range: ±10.500 V

Maximum output current: ±5 mA

Output impedance: 1 kΩ (nominal value)
+15V

+15V
1k

AUX OUT1AUX OUT2

-15V
-15V

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LI 5655 / LI 5660

3.2 I/O Connector

3.2.5 Other I/O Connectors
1) External 10 MHz Synchronization (10 MHz IN)
Input impedance: 1 kΩ (nominal value), AC coupling

Signal level: 0.5 Vp-p to 5 Vp-p

Non-destructive maximum input voltage: 10 Vp-p

Floating voltage (allowable voltage to ground): ±42 Vpeak (DC＋AC)

2200p
10MHz IN

330k

EXT
REF
CKT

1M

±42Vpk2) Trigger Input (TRIG IN)
Trigger input to start recording to the internal data memory.
Input impedance: 10 kΩ (nominal value)

Signal level: TTL (Low 0.8 V or less, High 2.6 V or more)

Non-destructive maximum input voltage: ±15 V

+3.3V

10 k

+3.3V

CMOS
LOGIC

TRIG IN
10 k

3) Power Output for Preamplifier (PREAMP POWER)
The ground for the power output for the preamplifier is a signal ground.
Maximum output current: ±100 mA
3 Pin numbers andconnections
1: +15V
2: 0V
3: -15V
4 4: 0V

2

1！ CAUTION

PREAMP POWER is intended to supply power to the external amplifier. Do not use it
for any other purpose, because doing so will adversely affect measurements or may
cause a failure.

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LI 5655 / LI 5660

3.3 Overview of the Measurement Screen

3.3 Overview of the Measurement Screen
3.3.1 Types and Switching between Measurement Screens
There are 3 types of measurement screen displays: Normal, Large, and Fine measurement screens.
When the SCRN key is pressed, the screen is changed sequentially as follows.
a) Normal Measurement Screen (Default)
Displays the measured values, bar graphs, and main settings in a well-balancedmanner.
b) Large Measurement Screen
Displays the expanded measured values and bar graphs.
The setting information display area is smaller.
c) Fine Measurement Screen
As much setting information as possible is displayed.
The measured value display area is smaller.
There is no bar graph display. Instead DATA1 to DATA4 are all displayed.
The SCRN / EXIT key is also used to move to the upper-level operation screen and return to themeasurement screen.

3.3.2 Measurement Screen
The following shows an example of each measurement screen display (when the detection mode is
SINGLE).
1) Normal Measurement Screen
Output connector

Measurement
parameter

Measured value

Status display area

Detection mode
display
Input connector
Input coupling
Bar graph

Signal ground
Detector icon
Sensitivity
Dynamic reserve

Sine wave
amplitude

Time constantAttenuation slope

Phase shift
amountSynchronous filter
Synchronous frequency (fundamental wave)

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Reference signal setting

LI 5655 / LI 5660

3.3 Overview of the Measurement Screen2) Large Measurement Screen
Measured value
Offset icon
Outputconnector
Arithmetic function
icon

Parameter

Bar graph

Dynamic reserve

Detector icon

Sensitivity

Time constantSynchronous frequency(fundamental wave)

3) Fine Measurement Screen
Output connectors (all 4 output displays)
Signal input setting
Power frequency
notch filter setting
AUX IN setting
AUX OUT setting

Offset adjustment
Arithmetic function
setting

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LI 5655 / LI 5660

3.3 Overview of the Measurement Screen

3.3.3 Details of the Measurement Screen
The following describes the status display area and measurement screen for two-frequency measurement.
■ Status Display Area
The following describes the icons displayed in the status display area.

Display at sensitivity
auto setting

Other over-level display exampls

StatusUNLOCKOUTPUT,
etc.

HEAT

SENS
PSD
10MHz
TGWait, Etc.

UCAL

Display when recording themeasured value

Description
Indicates out-of-sync. The signal is not synchronized with the reference signal.
The reference signal may not be connected or set correctly, or the reference signal
level may be low, or the signal may be outside the measurement frequency range.
Indicates signal over-level.
Indicated if the input signal is large, the amplifier is saturated, or the time constantfilter after the phase sensitive detector is saturated.
For details,  "4.7.3 Signal Over-level Display and Monitor Output."
Indicates overheat condition. Indicated if the internal temperature of the product isextremely high. If this indication appears when the ambient temperature is 40℃ orless and the installation is correct, a failure has occurred, so contact NF Corporationor one of our representatives.
Indicated during operation of auto sensitivity adjustment.
"ONCE" is displayed only during automatic sensitivity adjustment operation once.
Indicated during operation of auto PSD offset adjustment.
Indicates whether external 10 MHz synchronization is valid or invalid.
Indicates waiting for an external trigger.
"REC" is indicated while the measured value is being recorded
For details,  " LI 5655 / LI 5660Instruction Manual (Remote Control)""5. Description of Commands": TRIGger:SOURce"
Indicates the uncalibrated state. Indicated if the calibration information of the
product is lost due to a failure and the specified performance cannot be maintained.
A failure has occurred, so contact NF Corporation or one of our representatives.

■ Detection Mode Display
If the detection mode is changed, the displayed icon is changed accordingly.
: SINGLE

Single mode (normal single frequency measurement): DUAL1

Fractional Harmonic mode

: DUAL2

Independent frequency mode

: CASCADE

Cascade mode

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LI 5655 / LI 5660

3.3 Overview of the Measurement Screen■ Harmonic Measurement Display
The following describes the screen display for the harmonic setting.
If SINGLE or DUAL1 is set for the detection mode and the HARMONICS setting is enabled,
harmonic symbol "n" is added to the end of the measurement parameter.
Furthermore, the harmonic order is displayed next to the synchronous frequency (fundamental wave)
display.
Harmonic symbol (measurement parameter)

Phase shift amount of
the Primary PSD
Phase shift amount of
the secondary PSD
Fractional harmonic settingof the Primary PSD

Harmonics setting of the secondary PSD■ Display of Dual-Frequency Display
The following describes the screen display for the harmonic setting.
If the detection mode is DUAL2 or CASCADE, the primary frequency and secondary frequency aredisplayed.
Phase shift amount of
the Primary PSD

Primary frequency
display

Phase shift amount of
the secondary PSD

Secondaryfrequency display

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LI 5655 / LI 5660

3.3 Overview of the Measurement Screen

3.3.4 Operations in the Measurement Screen
Some of the parameters can be set as follows even in the measurement screen.
Simple operation keys
Up/down keys

Left/right cursor keys

Where to operate
Function
Simple operationkeys
  / PRI | SEC Select the detector
PRI (Primary PSD)  SEC (secondary PSD) * Can be used only when the detection mode is DUAL1, DUAL2, or
CASCADE
Select dynamic reserve / DR
(For details,  "4.7 Sensitivity and Dynamic Reserve Setting"
LOW  MED  HIGH 
Select the attenuation slope for the time constant filter
 / SLOPE
6dB  12dB  18dB  24dB 
Selectthe DATA1 or DATA2 parameter / DATA(For details,  "4.3 Measurement Parameter Setting, Output, andDisplay")
SINGLE(Before change ）R-θ  X-Y 
DUAL1(Before change ）Rpn-θpn  Xpn-Ypn  Xsn-Ysn  Xpn-Xsn 
DUAL2 / CASCade(Before change ）Rp-θp  Xp-Yp  Xs-Ys  Xp-Xs * DATA3 and DATA4 are not changed.
Manual trigger
For details,  " LI 5655 / LI 5660 Instruction Manual (Remote Control)""5. Description of Commands": TRIGger:SOURce
Up/down keys
Select the sensitivity (SENS)
Left/right cursor keys Select the time constant (TC) / TRIG■ Changing the Sensitivity and Time ConstantParameters in the setting value fields of a color different from theSetting value
fieldsbackground color, such as the sensitivity and time constant, can be
set using a simple operation key even in the measurement screen.

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LI 5655 / LI 5660

3.4 Overview of the Operation Screen

3.4 Overview of the Operation Screen
3.4.1 Operation Keys and MODIFY Knob
The advanced settings of the LI 5655 / LI 5660 are configured in the operation screen.
Soft key
titlesSoft keys

Operation screen
selection keys
CLR key

Up/down keys

CMD
SEL
MENU>
MENU>
Left/right cursor keys

Modify knob

SCRN / EXIT key

Operation Screen Selection Key

Down key

Displays the operation screen for each function.
Press the key to move to the corresponding operation screen (top page).
Soft Key
Operation key whose function changes for each operation screen.
A title indicating the function of each soft key is displayed at the right end of theoperation screen.
Left/right cursor keys
Select the digit to change (cursor digit) when entering a multi-digit numerical value.
The cursor does not go farther than the left or right end.
Up/Down Keys / MODIFY Knob
Both have the same function.
Change digits higher than the cursor digit when setting a numerical value.
Switch sequentially between options when selecting one option from multiple options.
CLR Key
Clear the set value.
SCRN / EXIT Key
Go to the next higher-level operation screen or return to the original measurement
screen.
Procedure:
1) Press the operation screen selection key that includes the function you wish to set.
2) Select the soft key where the name of the function you wish to set is displayed.
3) Change the parameter using the up/down keys, MODIFY knob, etc.
4) Press the SCRN / EXIT key to return to the measurement screen.

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LI 5655 / LI 5660

3.4 Overview of the Operation Screen

Operation Screen Selection Key Function List:

Key name

Screen nameMain function{Auto Setting Screen}

Auto setting of the sensitivity, time constant, etc.

{Output Signal Setting
Screen}Select the measurement parameter for DATA1 to 4.
Specify ratio arithmetic processing, normalize
arithmetic processing, etc.

{Sensitivity Setting Screen}

Set the sensitivity and dynamic reserve{Time Constant Filter Setting
Screen}Set the time constant, attenuation slope (SLOPE),
and synchronous filter (SYNC)
Select the input connector
Select the input coupling
Select the signal groundSet the line filter
Select the I-V conversion gain for the current input{Input Signal Selection
Screen}{Phase Adjustment Screen}{Reference Signal Setting
Screen}{Auxiliary I/O Setting Screen}{Utility Screen}

Set the phase adjustment range
Select the reference signal and polarity
Set the frequency and output amplitude of theinternal oscillator
Set the harmonics (harmonic order, etc.)
Set the detection mode
Set the AUX IN smoothing
Set the AUX OUT voltage
Reset the setting
Save and recall from the setting memory
Set the remote control interface
System setting (maintenance, etc.)

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LI 5655 / LI 5660

3.4 Overview of the Operation Screen

3.4.2 Operation Screen Configuration
Signal input settings / measured values(Same as the details measurement screen)

Soft key title

Soft key

CMD
SEL
MENU>
Screen title

MENU>

SCRN Title
Setting, Value

Current
settings

Setting range
Shows the setting range, etc.

Clear markIndicates that the CLR key can be used.

Indicates that the operation using the MODIFY knob is enabled.

Soft keys are classified into the following types.
Operation Command (CMD)
Execute a particular operation. Execute auto setting, etc.
A vertical bar (" | ") on a key indicates the separation of options. For "ON｜OFF" etc., every time
the key is pressed, ON and OFF are switched and executed.
Selection (SEL)
Select the setting item. The selected setting item can be changed by moving the cursor in theoperation screen and using the up/down keys and MODIFY knob.
A vertical bar (" | ") on a key indicates the separation of options. For "PRI｜SEC" etc., every time
the key is pressed, PRI and SEC are switched and selected.
Movement to a Lower-Level Screen (MENU>)
If ">" is at the end of the soft key name, you can move to a related lower-level operation screen.
Clear Mark・ CLR: Clear the entire string that was entered.

・ CLR

: When entering a multi-digit numerical value, the digits lower than the cursor
position are set to 0 .
When using

1.23456
Cursor position

CLR

1.23000
Clear range

Note that soft key titles CMD, SEL, and MENU> are examples for explanation.
They differ from the titles that are actually displayed.

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LI 5655 / LI 5660

3.5 Operation Tree

3.5 Operation Tree
The following shows the operation tree for operating the LI 5655/ LI 5660 from the panel.
For key and screen notations, refer to "3.1 Panel Part Names and Operations".
*1: This symbol indicates that the tree is omitted because the lower-level operation tree is the same asthat of detection mode SINGLE.
*2: This symbol indicates that the tree is omitted because the lower-level operation tree is the same asthat of detection mode DUAL1.

For details, "3.5.2 Operation Tree in the Measurement Screen (SINGLE)""3.5.3 Operation Tree in the Operation Screen (DUAL1)""3.5.4 Operation Tree in the Operation Screen (DUAL2/CASCADE)"

3.5.1 Operation Tree in the Measurement Screen
Front Panel_ SCRN_ / EXIT key : Select Measurement Screen (Normal | Large | Fine)(Simple Operation Keys)
 / PRI | SEC: Select Detector

 / DR: Select Dynamic Reserve

 / SLOPE: Select Attenuation Slope / DATA: Select Output Signal

 / TRIG: Manual Trigger (External Reference Signal)

Up/Down Keys

: Select Sensitivity

Left/Right Cursor Keys

: Select Time Constant

CLR_ / LOCAL Key: Change to local state (Panel Operation)

Hold Down _CLR_: Key Lock, Lamp Off, and Cancel(Operation Screen Selection Key)
_AUTO_: {Auto Setting Screen}_DATA_: {Output Signal Setting Screen}_SENS_: {Sensitivity Setting Screen}_TC_: {Time Constant Setting Screen}_SIG_: {Input Signal Setting Screen}_PHASE_: {Phase Adjustment Screen}_REF_: {Reference Signal Setting Screen}_AUX_: {Auxiliary I/O Setting Screen}_UTIL_: {Utility Screen}

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LI 5655 / LI 5660

3.5 Operation Tree

3.5.2 Operation Tree in the Measurement Screen (SINGLE)
The following shows the operation tree when the detection mode is SINGLE (normal single frequency)(Operation Screen Selection Key)
_AUTO_ : {Auto Setting Screen}[_MEASURE_]: Simple Measurement Setting[_SENS_]: Auto Sensitivity Setting[_TIME CONST_]: Auto Time Constant Setting[_PHASE_]: Auto Phase Adjustment_DATA_ : {Output Signal Setting Screen}[_BASIC>_]: {Basic Measurement Parameter Setting Screen}[_R-θ_]: Assign R to DATA1 and θ to DATA2[_X-Y_]: Assign X to DATA1 and Y to DATA2[_X-AUX1_]: Assign X to DATA1 and AUX1 to DATA2[_AUX1-AUX2_]: Assign AUX1 to DATA1 and AUX2 to DATA2[_NOISE-AUX1_]: Assign NOISE to DATA1 and AUX1 to DATA2[_CUSTOM>_]: {Custom Measurement Parameter Setting Screen}[_DATA1_]: Set Custom Measurement Parameter for DATA1[_DATA2_]: Set Custom Measurement Parameter for DATA2[_DATA3_]: Set Custom Measurement Parameter for DATA3[_DATA4_]: Set Custom Measurement Parameter for DATA4[_OUTPUT>_]: {Output On / Off Setting Screen}[_DATA1 ON｜OFF_]: Set Output to On or Off for DATA1[_DATA2 ON｜OFF_]: Set Output to On or Off for DATA2[_DATA3 ON｜OFF_]: Set Output to On or Off for DATA3[_DATA4 ON｜OFF_]: Set Output to On or Off for DATA4[_NOISE_]: {NOISE Density Measurement Setting}[_OFFSET>_]: {Offset Adjustment Screen}[_AUTO once_]: XY Offset Auto Adjustment[_X｜Y_]: XY Switching[_OFFSET_]: Offset Value Setting[_ON｜OFF_]: Offset On / Off Setting

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LI 5655 / LI 5660

3.5 Operation Tree[_MATH>_]: {Math Selection Screen}_[_EXPAND>_]: {Expansion Setting Screen}[_RX_]: R and X Expansion Factor Setting[_Y_]: Y Expansion Factor Setting[__NORM>_]: {Normalize Setting Screen}[_NORMALIZE_]: Select Normalize Arithmetic expression[_STD>_]: {Standard Value Setting Screen}[_x10_]: Move Decimal Point to Right[_÷10_]: Move Decimal Point to Left[_USER UNIT_][__RATIO>_]: User Unit Setting: {Ratio Setting Screen}[_K_]: Ratio Scale Factor Setting_SENS_ : {Sensitivity Setting Screen}[_SENS_]: Sensitivity Setting[_DR_]: Dynamic Reserve Switching[_AUTO_]: Sensitivity Setting Enable or Disable Setting_TC_ : {Time Constant Filter Setting Screen}[_FILTER ]: Select Time Constant Filter[_TC_]: Time Constant Setting[_SLOPE_]: Select Attenuation Slope[_PSD ADJ>_]: {PSD Input Offset Adjustment Screen}[_AUTO once>_]: {Adjustment Confirmation Screen}[_Exec_]: Execute Auto Adjustment[_Cancel_]: Cancel Auto Adjustment[_AUTO_]: Execute and Hold Continuous Auto Adjustment[_DEFAULT_]: Reset Adjustment (Factory Default Value)[_SETLG TIME_]: Set Response Time for Auto Adjustment_SIG_ : {Input Signal Selection Screen}[_SIG IN_]

: Select Input Connector[_1M｜100M_]: I-V Conversion Gain Switching (I Input Only)[_50Ω｜1MΩ_]: Input Impedance Switching (HF *3 Input Only)[_COUPLING_]: Select Input Coupling (A, A-B, and I Input Only)[_GROUND_]: Select Signal Ground[_LINE NOTCH>_]: {Line Filter Setting Screen}[_LINE FREQ>_]: Line Frequency Selection Screen*3: Only the LI 5660 is equipped with the HF input.

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LI 5655 / LI 5660

3.5 Operation Tree

_PHASE_ : {Phase Adjustment Screen}[_+90°R_]: Phase Shift Amount 90° Increase[_-90°R_]: Phase Shift Amount 90° Decrease[_ZERO_]: Set Phase Shift Amount to 0°_REF_ : {Reference Signal Setting Screen}[_SOURCE_]: Select Reference Signal Source[_EDGE_]: Select Reference Signal Waveform[_OSC SET>_]: {Oscillator Setting Screen}[_FREQ>_]: {Frequency Setting Screen}[_x10_]: Move Decimal Point to Right for Frequency[_÷10_]: Move Decimal Point to Left for Frequency[_AMPTD>_]: {Amplitude Setting Screen}[_AMPTD>_]: Amplitude Setting[_x10_]: Move Decimal Point to Right for Amplitude[_÷10_]: Move Decimal Point to Left for Amplitude[_ RANGE_]: Amplitude Range Setting[_10MHz In>_]: {External 10 MHz Setting Screen}[_ON｜OFF _][_HMNC>_]: 10 MHz Enable or Disable: {Harmonic Setting Screen}[_ON｜OFF _]: Harmonic On / Off[_n_]: n-order Harmonic Setting[_m_]: 1/m Fractional Harmonic Setting[_DET MODE>_]: {Detection Mode Setting Screen}[_Exec_]: Execute Detection Mode Setting[_Cancel_]: Cancel Detection Mode Setting_AUX_ : {Auxiliary I/O Setting Screen}[_AUX IN>_]: {Auxiliary Input Setting Screen}[_IN1_]: Select AUX IN1 Smoothing Time Constant[_IN2_]: Select AUX IN2 Smoothing Time Constant[_INPUT>_]: {AUX IN Setting Screen}[_AUX IN1 ON｜OFF_]: AUX IN1 On / Off[_AUX IN2 ON｜OFF_]: AUX IN2 On / Off[_AUX OUT>_]: {Auxiliary Output Setting Screen}[_OUT1_]: AUX OUT1 Voltage Setting[_OUT2_]: AUX OUT2 Voltage Setting

To be continued

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LI 5655 / LI 5660

3.5 Operation Tree_UTIL_ : {Utility Screen}[_RESET>_]: {Reset Setting Screen}[_Exec_]: Execute Reset[_Cancel_]: Cancel Reset[_MEMORY>_]: {Setting Memory Screen}[_MEMORY>_]: Select Setting Memory[_NAME_]: Change Setting Memory Name[_RECALL>_]: {Setting Memory Recall Screen}[_Exec_]: Execute Setting Memory Recall[_Cancel_]: Cancel Recall[_SAVE>_]: {Setting Memory Save Screen}[_Exec_]: Execute Setting Memory Save[_Cancel_]: Cancel Save[_CLEAR>_]:{ Setting Memory Clear Screen}[_Exec_]: Execute Setting Memory Clear Individually[_Cancel_]: Cancel Setting Memory Clear[_INTERFACE>_]: {Interface Setting Screen}[_USB>_]: {USB Information Screen}[_Exec_]: Execute USB Communication Selection[_GPIB>_]: {GPIB Setting Screen}[_Exec_]: Execute GPIB Communication Selection[_RS232>_]: {RS232 Setting Screen}[_BAUD RATE_]: Baud Rate Setting[_FLOW CONTROL_]: Flow Control Setting[_TERMINATOR_]: Terminator Setting[_Exec_]: Execute RS232 Communication Selection[_LAN>_]: {LAN Setting Screen}[_Manual>_]: {Address Manual Setting Screen}[_IP ADDR_]: IP Address Setting[_MASK_]: Subnet Mask Setting[_GATEWAY_]: Default Gateway Setting[_DNS_]: DNS Setting[_Exec_]: Exectute LAN Communication Selection[_Auto>_]: {Address Auto Setting Screen}[_Exec_]: Exectute LAN Communication Selection：{LAN Reset Screen}[_Reset>_][_Exec_]：Execute LAN Setting Reset[_Cancel_]：Cancel Execution

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LI 5655 / LI 5660

3.5 Operation Tree[_SYSTEM>_]: {System Setting Screen}[_VERSION>_]: {Version Information Screen}[_SELF TEST>_]: {Self-Diagnosis Screen}[_Exec_]: Execute Self-Diagnosis[_Cancel_]: Cancel Self-Diagnosis[_SERVICE>_]: {Maintenance Information Screen}[_INIT>_]: {Initialize Execution Screen}[_Exec_]: Execute Initialize[_Cancel_]: Cancel Initialize(Other Operations)
Front Panel
MODIFY Knob
Select the parameter or change the numerical value higher than the cursor digit (digit on which
the cursor is placed)
Up/down keys
Same as the MODIFY knob
Left/right cursor keys
Move the cursor to enter a multi-digit numerical value_CLR_
Clear a numerical value, string, etc.
_SCRN_ / EXIT
Move to a higher level setting screen or return to the original measurement screen

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LI 5655 / LI 5660

3.5 Operation Tree

3.5.3 Operation Tree in the Operation Screen (DUAL1)
The following shows the operation tree when the detection mode is DUAL1 (fractional harmonic mode)(Operation Screen Selection Key)
_AUTO_ : {Auto Setting Screen}[_MEASURE_]: Simple Measurement Setting[_SENS_]: Auto Sensitivity Setting[_TC_]: Auto Time Constant Setting[_PHASE PRI_]: Primary PSD Auto Phase Adjustment[_PHASE SEC_]: Secondary PSD Auto Phase Adjustment_DATA_ : {Output Signal Setting Screen}[_BASIC>_]: {Basic Measurement Parameter Setting Screen}[_Rp-θp_]: Assign Rp to DATA1 and θp to DATA2[_Rp-Rs_]: Assign Rp to DATA1 and Rs to DATA2[_Xp-Xs_]: Assign Xp to DATA1 and Xs to DATA2[_Xp-AUX1_]: Assign Xp to DATA1 and AUX1 to DATA2[_NOISE-AUX1_]: Assign NOISE to DATA1 and AUX1 to DATA2[_CUSTOM>_]: {Custom Measurement Parameter Setting Screen}[_DATA1_]: Set Custom Measurement Parameter for DATA1[_DATA2_]: Set Custom Measurement Parameter for DATA2[_DATA3_]: Set Custom Measurement Parameter for DATA3[_DATA4_]: Set Custom Measurement Parameter for DATA4[_OUTPUT>_]: {Output On or Off Setting Screen}[_DATA1 ON｜OFF_]: Set Output to On or Off for DATA1[_DATA2 ON｜OFF_]: Set Output to On or Off for DATA2[_DATA3 ON｜OFF_]: Set Output to On or Off for DATA3[_DATA4 ON｜OFF_]: Set Output to On or Off for DATA4[_NOISE_]: NOISE Density Measurement Setting[_OFFSET>_]: {Offset Adjustment Screen}[_PRI｜SEC_]: Detector Switching[_AUTO once_]: XY Offset Auto Adjustment[_X｜Y_]: XY Switching[_OFFSET_]: Offset Value Setting[_ON｜OFF_]: Offset On / Off Setting

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3.5 Operation Tree[_MATH>_]: {Math Selection Screen}: {Expansion Setting Screen}_[_EXPAND>_][_PRI｜SEC_]: Detector Switching[_RX_]: R and X Expansion Factor Setting[_Y_]: Y Expansion Factor Setting[__NORM>_]: {Normalize Setting Screen}[_NORMALIZE_]: Select Normalize Arithmetic expression[_STD>_]: {Standard Value Setting}[_x10_]: Move Decimal Point to Right[_÷10_]: Move Decimal Point to Left[_USER UNIT_][__RATIO>_]: User Unit Setting: {Ratio Setting Screen}[_RATIO_]: Select Ratio Atithmetic Expression[_K_]: Ratio Scale Factor Setting_SENS_ : {Sensitivity Setting Screen}[_PRI｜SEC_]: Detector Switching[_SENS_]: Sensitivity Setting[_DR_]: Dynamic Reserve Switching[_AUTO_]: Sensitivity Auto Setting Enable or Disable_TC_ : {Time Constant Filter Setting Screen}[_PRI｜SEC_]: Detector Switching[_FILTER ]: Select Time Constant Filter[_TC_]: Time Constant Setting[_SLOPE_]: Select Attenuation Slope[_PSD ADJ>_]: {PSD Input Offset Adjustment Screen}[_AUTO once>_]: {Adjustment Confirmation Screen}[_Exec_]: Execute Auto Adjustment[_Cancel_]: Cancel Auto Adjustment[_AUTO_]: Execute and Hold Continuous Auto Adjustment[_DEFAULT_]: Reset Adjustment (Factory Default Value)[_SETLG TIME_]: Set Response Time for Auto Adjustment_SIG_ : {Input Signal Selection Screen}*1_PHASE_ : {Phase Adjustment Screen}[_PRI｜SEC_]: Detector Switching[_+90°R_]: Phase Shift Amount 90° Increase[_-90°R_]: Phase Shift Amount 90° Decrease[_ZERO_]: Set Phase Shift Amount to 0°
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3.5 Operation Tree

_REF_ : {Reference Signal Setting Screen}[_SOURCE_]: Select Reference Signal Source[_EDGE_]: Select Reference Signal Waveform[_OSC SET>_]: {Oscillator Setting Screen}[_FREQ>_]: {Primary PSD Frequency Setting Screen}[_x10_]: Move Decimal Point to Right for Frequency[_÷10_]: Move Decimal Point to Left for Frequency[_AMPTD>_]: {Amplitude Setting Screen}[_AMPTD>_]: Amplitude Setting[_x10_]: Move Decimal Point to Right for Amplitude[_÷10_]: Move Decimal Point to Left for Amplitude[_ RANGE_]: Amplitude Range Setting[_10MHz In>_]: {External 10 MHz Setting Screen}[_ON｜OFF _][_HMNC>_]: 10 MHz Enable / Disable: {Harmonic Setting Screen}[_PRI HMNC ON｜OFF _]: Primary PSD Harmonic On / Off[_PRI n_]: N-order Harmonic Setting (Primary PSD)[_PRI m _]: 1/m Fractional Harmonic Setting (Primary PSD)[_SEC HMNC ON｜OFF _]: Secondary PSD Harmonic On / Off[_SEC n_]: n-order Harmonic Setting (Secondary PSD)[_DET MODE>_]: {Detection Mode Setting Screen}[_Exec_]: Execute Detection Mode Setting[_Cancel_]: Cancel Detection Mode Setting_AUX_ : {Auxiliary I/O Setting Screen}*1_UTIL_ : {Utility Screen}*1(Other Operations)
Front Panel *1

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3.5 Operation Tree

3.5.4 Operation Tree in the Operation Screen (DUAL2/CASCADE)The following shows the operation tree when the detection mode is DUAL2 (independent frequency mode)and CASCADE (cascade mode).
(Operation Screen Selection Keys)_AUTO_ : {Auto Setting Screen}*2_DATA_ : {Output Signal Setting Screen}*2_SENS_ : {Sensitivity Setting Screen}*2_TC_ : {Time Constant Filter Setting Screen}*2_SIG_ : {Input Signal Selection Screen}*1_PHASE_ : {Phase Adjustment Screen}*2_REF_ : {Reference Signal Setting Screen}[_SOURCE_]: Select Reference Signal Source[_EDGE_]: Select Reference Signal Waveform[_OSC SET>_]: {Oscillator Setting Screen}[_PRI FREQ>_]: {Primary PSD Frequency Setting Screen}[_x10_]: Move Decimal Point to Right for Frequency[_÷10_]: Move Decimal Point to Left for Frequency[_SEC FREQ>_]: {Secondary PSD Frequency Setting Screen}[_x10_]: Move Decimal Point to Right for Frequency[_÷10_]: Move Decimal Point to Left for Frequency[_AMPTD>_]: {Amplitude Setting Screen}[_AMPTD>_]: Amplitude Setting[_x10_]: Move Decimal Point to Right for Amplitude[_÷10_]: Move Decimal Point to Left for Amplitude[ RANGE_]: Amplitude Range Setting[_SEL CH>_]: {OSC Output Oscillator Selection Screen}[_10MHz In>_]: {External 10 MHz Setting Screen}[_ON｜OFF _][_DET MODE>_]: 10 MHz Enable / Disable: {Detection Mode Setting Screen}[_Exec_]: Execute Detection Mode Setting[_Cancel_]: Cancel Detection Mode Setting

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3.6 Operation Screen Reference_AUX_ : {Auxiliary I/O Setting Screen}*1_UTIL_ : {Utility Screen}*1(Other Operations)
Front Panel *1

3.6 Operation Screen Reference
The following shows each operation screen.

Detector switching soft key《Single Frequency Measurement》

Detector display
Detector display《Dual Frequency Measurement_PRI》
Detector icon

《Dual Frequency Measurement_SEC》

Detector icon

■ Soft Key Displayed for the Frequency Constant Setting[PRI｜SEC]
This soft key is not displayed when the detection mode is SINGLE, but is displayedwhen the detection mode is DUAL1, DUAL2, or CASCADE.
If the operation screen is SENS , TC , or PHASE and the TOP menu is displayed,
the detector to be set can be switched to PRI (Primary PSD) or SEC (Secondary PSD).
You can identify which detector is selected by the detector icon ("PRI" or "SEC") on thesetting screen.

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3.6 Operation Screen Reference

3.6.1 AUTO : {Auto Setting Screen}
When you enter this screen, it switches to the auto setting screen.
{Auto Setting Screen}《Single Frequency Measurement》《Dual Frequency Measurement》[ MEASURE ]: Simple Measurement Setting
Execute the simple measurement setting.
Execute the auto setting in order of TIME CONST → SENS → PHASE PRI below.
For the dual frequency measurement, the setting is executed in order of PHASE SEC →PHASE PRI.
[ SENS ]: Auto Sensitivity Setting
Execute the auto sensitivity setting. For details,  "4.7 Sensitivity and Dynamic Reserve
Setting"
Adjust the sensitivity (SENS) and dynamic reserve (DR) according to the magnitude of
the signal and noise.
The dynamic reserve setting is shared by the primary and secondary PSD in the dual
frequency measurement.
[ TIME CONST ]: Auto Time Constant Setting
Execute the auto time constant filter setting. For details,  "4.6 Time Constant Filter
Setting and Characteristics"
Set the time constant (TC) and attenuation slope (SLOPE) according to the frequency of
the reference signal.
If the synchronous filter function (SYNC: integer period moving average filter) is set toOn, it is canceled.
[ PHASE ]: Auto Phase Adjustment
For dual frequency measurement, the key name is [ PHASE PRI ].
Execute the auto phase adjustment. For details,  "4.8 Phase Adjustment"
Set the phase shift amount for the reference signal to be provided for PSD so the Y and θ
output become zero.
[ PHASE SEC ]: Auto Phase Adjustment
For single frequency measurement, this soft key is not displayed.
For dual frequency measurement, auto phase adjustment of the secondary PSD is
executed.

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3.6 Operation Screen Reference

Operation Message
When the auto setting is completed, "Done" is displayed for a short time and then thescreen returns to the measurement screen.
When the process is interrupted (canceled), "Canceled" is displayed.
When the following operations is performed, Simple measurement setting andsensitivity setting, It will be forcibly canceled.
 When the offset value is changed using the ＿DATA＿ key and [ OFFSET> ] soft key.
 When the arithmetic processing function is changed using the ＿DATA＿ key and[ MATH> ] soft key.
 When a change is made to the time constant filter settings using the ＿TC＿ key.
 When a change is made to the input connector settings using the ＿SIG＿ key.
 When the phase shift amount is changed using the ＿PHASE＿ key.
 When a change is made to the reference signal settings using the ＿REF＿ key.
 When the sensitivity or dynamic reserve is changed from the measurement screen or
operation screen.
Error Message
If the auto setting fails, "Error" and an error message are displayed.
"Error No.-206 Auto-once failed duo to unlock"
The auto setting failed because the signal is not synchronized with the reference
signal (REF IN, SIGNAL).

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3.6 Operation Screen Reference

3.6.2 DATA : {Output Signal Setting Screen}
When you enter this setting screen, you can set the measurement parameters for DATA1 to DATA4.
[ BASIC> ]: {Basic Measurement Parameter Setting Screen}
Pressing this soft key switches the soft key display to a frequently used combination of
measurement parameters (refer to the figure below). When the switched soft key is
executed, values are set in DATA1 and DATA2 at one time. DATA3 and DATA4 are notchanged.
Combinations of basic measurement parameters are shown in the tables below.
For example, if [X-Y] is executed in single frequency measurement, measurement
parameters X and Y are set in DATA1 and DATA2, respectively.
{Output Signal Setting Screen}{Basic Measurement Parameter Setting Screen}《Single Frequency《Dual Frequency

Measurement》

Measurement》《Combinations for Single Frequency Measurement》
Measurement parameter
Soft key
DATA1
DATA2
DATA3
R
θ
No Change[ R－θ ]XY
No Change[ X－Y ]X
AUX1
No Change[ X－AUX1 ]
AUX1
AUX2
No Change[ AUX1－AUX2 ]
NOISE
AUX1
No Change[ NOISE－AUX1 ]DATA4No Change
No Change
No Change
No Change
No Change《Combinations for Dual Frequency Measurement》
Measurement parameter
Soft key
DATA1
DATA2
DATA3
Rp
θp
No Change[ Rp－θp ]Rp
Rs
No Change[ Rp－Rs ]Xp
Xs
No Change[ Xp－Xs ]Xp
AUX1
No Change[ Xp－AUX1 ]
NOISE
AUX1
No Change[ NOISE－AUX1 ]DATA4No Change
No Change
No Change
No Change
No Change

Measurement parameter symbols

Xpn
Harmonic On /Off: When n is displayed, the harmonic function is On
PSD: p indicates the primary PSD, and s indicates the secondary PSD(displayed only for dual frequency measurement)
Measurement parameters: R, θ, X, and Y

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3.6 Operation Screen Reference[ CUSTOM> ]: {Custom Measurement Parameter Setting Screen}
Pressing this soft key switches the soft key from DATA1 to DATA4.
An individual parameter can be set in each DATA.
Parameters that can be set individually are shown in the tables below.
{Custom Measurement Parameter
Setting Screen}{Output Signal Setting Screen}《Measurement Parameters for Single Frequency Measurement》
Soft key

Measurement parameter[ DATA1 ]X｜R｜AUX1｜NOISE[ DATA2 ]Y｜θ｜AUX1｜AUX2[ DATA3 ]X｜R[ DATA4 ]Y｜θ《Measurement Parameters for Dual Frequency Measurement》
Soft key

Measurement parameter[ DATA1 ]Xp｜Rp｜Yp｜θp｜Xs｜Rs｜AUX1｜NOISE[ DATA2 ]Yp｜θp｜Xs｜Rs｜Ys｜θs｜AUX1｜AUX2[ DATA3 ]Xp｜Rp｜Yp｜θp｜Xs｜Rs[ DATA4 ]Yp｜θp｜Xs｜Rs｜Ys｜θs

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3.6 Operation Screen Reference[ OUTPUT> ]: {Output On / Off Setting Screen}
Pressing this soft key switches the voltage output for DATA1 to DATA4 individually to
ON (enable) and OFF (disable).
{Custom Measurement Parameter Setting Screen}{Output On / Off Setting Screen}■ Stopping the DATA OUT Output Connector
If Output ON / OFF is set to OFF (disable), the DATA OUT output is stopped (about 0 V) while themeasured value on the screen remains unchanged. The clock for the internal D/A converter stops sonoise (disturbance) is reduced and very small signal measurement is more immune to disturbance.

[ NOISE ]: NOISE Density Measurement Setting
When NOISE is selected for the measurement parameter, this soft key is displayed.
This soft key allows you to set the noise smoothing factor. The setting range is {1｜4｜16｜64}. The larger the factor, the smaller the fluctuation of the measured value (which is
proportional to the smoothing factor), but it will take some time for the value to becomestabilized.
{Output Signal Setting Screen}

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3.6 Operation Screen Reference[ OFFSET> ]: {Offset Adjustment Screen}
Pressing this soft key switches to {Offset Adjustment Screen}.
When you enter this setting screen, you can move through the digits using the left/right cursor keys andthen set the offset value using the MODIFY knob and up/down keys.
The offset value can be set individually for measurement parameters X and Y for eachdetector.
{Output Signal Setting Screen}{Offset Adjustment Screen}《Single Frequency《Dual Frequency

Measurement》

Measurement》[ PRI｜SEC ]: Detector Switching
For single frequency measurement, this soft key is not displayed.
For dual frequency measurement, the offset value can be set individually formeasurement parameters X and Y for each detector.
[ AUTO once ]: XY Offset Auto Adjustment
The offset is automatically adjusted once to set both measurement parameters X and Y
to zero.
When the offset auto adjustment is executed, the offset ON / OFF setting is set to ON.
[ X｜Y ]: XY Switching
Measurement parameters X and Y for setting the offset are switched.
[ OFFSET ]: Offset Value Setting
The cursor moves and the offset value can be set.
The setting range is {-105.000% to +105.000%}[ ON｜OFF ]: Offset ON / OFF Setting
The offset setting for measurement parameters X and Y is individually switchedbetween ON (enable) and OFF (disable).
Operation Message
When the auto adjustment is completed successfully, "Done" is displayed after theoffset adjustment value for a short time.
Error Message
If the auto setting fails, "Error" and an error message are displayed.
"Error No.-206 Auto-once failed duo to unlock"
The auto adjustment failed because the signal is not synchronized with thereference signal (REF IN, SIGNAL).
"Error No.-207 X,Y out of range"
The auto adjustment failed because the X and Y measured values are outside theadjustment range.

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3.6 Operation Screen Reference[ MATH> ]: {Math Selection Screen}
Pressing this soft key allows you to select from the arithmetic processing functions {OFF｜EXPAND｜NORMALIZE｜RATIO} for measurement parameters X, Y, and R.
{Output Signal Setting Screen}{Math Selection Screen}《OFF》

The soft key for each arithmetic
processing function is switched using《EXPAND》

the up/down keys or MODIFY knob.

《NORMALIZE》《RATIO》

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3.6 Operation Screen Reference

During each arithmetic function, When you press the [MEASURE] soft key or the [SENS] soft key ofthe ＿AUTO＿ key {Auto Setting Screen} or the [AUTO] soft key of the ＿SENS＿ key {Sensitivity
Setting Screen}, the arithmetic processing function is canceled.

[ EXPAND> ]: {Expansion Setting Screen}
When EXPAND is selected for the arithmetic processing function, the screen is
switched to {Expansion Setting Screen}.
A common expansion scale can be set for X and R, and an individual expansion scale
can be set for Y.
Disabling EXPAND is equivalent to expansion factor 1.
{Expansion Setting Screen}《Single Frequency Measurement》《Dual Frequency Measurement》[PRI | SEC]: Detector Switching
For single frequency measurement, this soft key is not displayed.
For dual frequency measurement, an expansion factor can be set individually for measurement
parameters R, X, and Y for each detector.
[RX]: R and X Expansion Factor Setting
Factors {1｜10｜100} can be set for measurement parameters R and X.
[ Y ]: Y Expand Setting
Factors {1｜10｜100} can be set for measurement parameter Y.

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3.6 Operation Screen Reference[ NORMALIZE > ]: {Normalize Setting Screen}
When NORMALIZE is selected for the arithmetic processing function, the screen is
switched to {Normalize Setting Screen}.
A normalize arithmetic processing is performed for the measured value for the
primary PSD measurement parameter X or R set for DATA1, and the result is
displayed and output for DATA1.
{Normalize Setting Screen}[NORMALIZE]: Select Normalize Arithmetic Expression
Normalize arithmetic expression can be selected from {%｜dB｜%FS}・%: (Measured value ÷ standard value) x 100 [%]・dB: 20 × log10 (|Measured value ÷ standard value|) [dB]・%FS

: (Measured value ÷ sensitivity setting) x 100 [%FS][ STD> ]: {Standard Value Setting Screen}
Pressing this soft key switches to {Standard Value Setting Screen}, where you can set thestandard value by moving the cursor.
The setting range of the standard value is {1 nV to 10 V for voltage measurement and 1 fA to 1
μA for current measurement (6-digit resolution)}.
[ ×10 ] : Move Decimal Point to Right
You can move the decimal point in the standard value to the right.
[ ÷10 ] : Move Decimal Point to Left
You can move the decimal point in the standard value to the left.
[ USER UNIT ]: User Unit Setting
Pressing this soft key allows you to set the user unit string by moving the cursor.
Up to 3 characters can be selected from { Blank, A to Z, a to z, 0 to 9, #, @,- } and specified

for the user unit string to be added after the numerical value. (Example: "USR")

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3.6 Operation Screen Reference[ RATIO > ] : {Ratio Setting Screen}
When RATIO is selected for the arithmetic processing function, the screen is switchedto {Ratio Setting Screen}.
A ratio arithmetic prosessing is performed using the measured value of primary PSD
measurement parameter Xp, Yp, or Rp as the numerator and the measured value ofauxiliary input AUX IN1 or secondary PSD measurement parameter Xs as thedenominator.
The ratio can be displayed and output by selecting the primary PDS measurement
parameter Xp, Yp, or Rp for DATA in the state of execution of the ratio arithmetic
processing.
When you enter this setting screen, you can move through the digits using theleft/right cursor keys and then set the ratio scale using the MODIFY knob andup/down keys.
{Ratio Setting Screen}《Single Frequency Measurement》《Dual Frequency Measurement》[ RATIO ] : Select Ratio Arithmetic Processing Function
You can select the ratio arithmetic expression from {RATIO1｜RATIO2}.
However, RATIO2 can be displayed and selected only when the detection mode is DUAL1 or
DUAL2.
RATIO
selection
RATIO1RATIO2

Contents of arithmetic expression
K×（primary PSD（Xp，Yp，Rp） ÷ AUX IN1）[%FS]

K×（secondary PSD（Xs，Ys，Rs） ÷ AUX IN1）[%FS]

K×（primary PSD（Xp，Yp，Rp）÷ secondary PSD Xs） [%FS]

Detection
mode
SINGLE
DUAL1
DUAL2
CASCADE
DUAL1
DUAL2

[ K ] : Ratio Scale Factor Setting
Pressing this soft key allows you to set the ratio scale by moving the cursor.
The setting range of the ratio scale is {0.1 to 10 (6-digit resolution)}.

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3.6 Operation Screen Reference

3.6.3 SENS : {Sensitivity Setting Screen}
When you enter this setting screen, you can adjust SENS (sensitivity) using the MODIFY knob andup/down keys.
{Sensitivity Setting Screen}《Single Frequency Measurement》《Dual Frequency Measurement》[ PRI｜SEC ] : Detector Switching
For single frequency measurement, this soft key is not displayed.
For dual frequency measurement, the sensitivity can be set individually for the primaryand secondary PSD's.
[ SENS ] : Sensitivity Setting
The sensitivity can be set.
[ DR ] : Dynamic Reserve
The dynamic reserve can be selected from {LOW｜MED｜HIGH}.
[ AUTO ] : Sensitivity Auto Setting
You can select whether to continuously automatically adjust or hold the sensitivity anddynamic reserve by selecting {AUTO｜HOLD} according to the magnitude of the signal
and noise.
If you press the [MEASURE] soft key or [SENS] soft key of the ＿AUTO＿ key {Auto Setting
Screen} during the continuous automatically adjustment, the continuous automaticallyadjustment will be canceled.

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3.6 Operation Screen Reference

3.6.4 TC : {Time Constant Filter Setting Screen}
When you enter this setting screen, you can set TC (time constant) using the MODIFY knob and up/downkeys.
{Time Constant Filter Setting Screen}《Single Frequency Measurement》《Dual Frequency Measurement》[ FILTER ] : Select Filter
For single frequency measurement, this soft key is not displayed.
For dual frequency measurement, the time constant filter can be set individually for the
primary and secondary PSD’s.
[ FILTER ] : Select Filter
The filter after the detector can be selected from {TC｜SYNC}.
・ TC: Time constant filter only

・ SYNC: Synchronous filter + time constant filter[ TC ] : Time Constant Setting
The time constant can be set to {1 μs to 50 ks (1-2-5 sequence)}.
[ SLOPE ] : Attenuation Slope Setting
The attenuation slope can be set to {6 dB｜12 dB｜18 dB｜24 dB}.

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3.6 Operation Screen Reference[ PSD ADJ> ] : {PSD Input Offset Adjustment Screen}
Pressing this soft key switches to {PSD Input Offset Adjustment Screen} to cancel the
input offset for PSD (phase sensitive detector).
For details, "5.7 PSD Input Offset Adjustment"{Adjustment Confirmation Screen}{PSD Input Offset Adjustment Screen}[ AUTO once> ] : {Adjustment Confirmation Screen}
Automatically adjusts the PSD input offset only once.
Pressing this soft key switches to {Adjustment Confirmation Screen}.
[ Exec ] : Execute Auto Adjustment
Executes the adjustment.
After the adjustment is completed, HOLD is set.
[ Cancel ] : Cancel Auto Adjustment
Returns to the PSD adjustment screen without executing the adjustment.
[ AUTO ] : Execute and Hold Continuous Auto Adjustment{AUTO｜HOLD} can be set for the continuous auto PSD input offset adjustment.
If HOLD is set, the last PSD input offset adjustment value is applied.
If AUTO is set, the PSD input offset is continuous automatically adjusted.
[ DEFAULT ] : Reset Adjustment (Factory Default Value)
Resets the PSD adjustment value (to the factory default value).
[ SETLG TIME ] : Set Response Time for Auto Adjustment
The time constant for the auto PSD input offset adjustment can be selected from {200ms｜750 ms｜3000 ms}.

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3.6 Operation Screen Reference

3.6.5 SIG : {Input Signal Selection Screen}
When you enter this setting screen, you can select the input connector using the MODIFY knob andup/down keys.
*1: Only the LI 5660 is equipped with the C and HF inputs.
{Input Signal Selection Screen}《C Input》*1《A / A-B Input》《HF Input》*1《I Input》[SIG IN] : Select Input Signal
Pressing this soft key allows you to select the input connector from {A｜A-B｜C *1｜I｜
HF *1}.
Furthermore, the soft key for a parameter that can be set is displayed according to theselected input.
[ 1M | 100M ] : Current to Voltage Convension Gain Switching
Displayed only when the I input is selected.
The current to voltage conversion factor can be selected from {1 M｜100 M}.
[ 1MΩ | 100M ] : Input Impedance Switching
Displayed only when the HF *1 input is selected.
The input resistance can be selected from {1 MΩ｜50 Ω}.
[ COUPLING ] : Input Coupling Selection
Displayed only when the A, A-B, or I input is selected.
The input coupling can be selected from {AC｜DC}. However, only the current to voltage
conversion coupling is available for the I input.
Input
A / A-BI
C *1
connector
Conversion――――――
1 M (106)
100 M (108)factor
Input
10 MΩ
1 MΩ
―――
―――
resistance
COUPLING
AC
AC｜DC
AC｜DC
Sensitivity
10 nV to 1 V
1 mV to 10 V 100 fA to 1 μA 10 fA to 10 nA
range
Frequency
0.5 Hz to 3 MHzrange
For details,  "4.5 Input Connector Setting and Connection"

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HF *1
―――
1 MΩ｜50 ΩAC
1 mV to 1 V
10 kHz to 11 MHz

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3.6 Operation Screen Reference[ GROUND ] : Select Signal GroundThe signal ground processing can be selected from {FLOAT｜GND}.
・FLOAT: Float from the enclosure (impedance to the enclosure 10 kΩ)・GND: Grounded to the enclosure (impedance to the enclosure 10 Ω

[ LINE NOTCH> ] : {Line Filter Setting Screen}
Pressing this soft key switches to {Line Filter Setting Screen}.
{Line Filter Setting Screen}

The line filter function (removal frequency) can be selected.
・When line frequency is 50 Hz: {THRU｜50 Hz｜100 Hz｜50 Hz＆100 Hz}
・When line frequency is 60 Hz: {THRU｜60 Hz｜120 Hz｜60 Hz＆120 Hz}[ LINE FREQ> ] : {Line Frequency Selection Screen}
Pressing this soft key switches to {Line Frequency Selection Screen}.
{Line Frequency Selection Screen}

The line frequency (fundamental) can be selected from {50 Hz｜60 Hz}.

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3.6 Operation Screen Reference

3.6.6 PHASE : {Phase Adjustment Screen}
When you enter this setting screen, you can move through the digits using the left/right cursor keys andthen adjust the phase shift amount for the reference signal using the MODIFY knob and up/down keys.
The setting range is {-180.000° to +179.999°}.
If the phase shift amount exceeds +179.999°, it wraps to -180.000°, and if it falls below -180.000°, it wraps
to +179.999°.
{Phase Adjustment Screen}《Single Frequency Measurement》《Dual Frequency Measurement》[ PRI | SEC] : Detector Switching
For single frequency measurement, this soft key is not displayed.
For dual frequency measurement, the phase shift amount can be set individually for the
primary and secondary PSD’s.
[ +90°R ] : Shift Amount 90° Increase
Press this soft key to increase the phase shift amount for the reference signal by 90°.
[ -90°R ] : Shift Amount 90° Decrease
Press this soft key to decrease the phase shift amount for the reference signal by 90°.
[ ZERO ] : Set Shift Amount to 0°
Press this soft key to set the phase shift amount for the reference signal to 0°.

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3.6 Operation Screen Reference

3.6.7 REF : {Reference Signal Setting Screen}
When you enter this setting screen, you can select SOURCE using the MODIFY knob and up/down keys.
*1: Only the LI 5660 is equipped with input connectors C and HF.
{Reference Signal Setting Screen}[ SOURCE ] : Select Reference Signal Source
The reference signal can be selected from {REF IN｜INT OSC｜SIGNAL}.
・ REF IN

: External reference signal (REF IN connector)

・ INT OSC

: Internal oscillator

・ SIGNAL: Measurement signal (for input connector A, etc.)[ EDGE ] : Select Reference Signal Waveform
Displayed only when REF IN is selected.
The waveform of the external reference signal can be selected from {SIN+｜TTL+｜TTL-}.
・ SIN+: Rise zero cross point of the sine wave, etc.
(Not displayed when the input connector is HF.)

・ TTL+: Rise edge of the TTL level square wave

・ TTL-: Fall edge of the TTL level square wave

[ OSC SET> ] : {Oscillator Setting Screen}
Pressing this soft key switches to {Oscillator Setting Screen} to set the internal oscillator
and sine wave output (OSC OUT).
{Oscillator Setting Screen}《Detection Mode SINGLE / DUAL1》《Detection Mode DUAL2 / CASCADE》

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3.6 Operation Screen Reference[ FREQ> ] : {Frequency Setting Screen}
Pressing this soft key switches to {Frequency Setting Screen } for the internal
oscillation frequency (primary PSD).
When you enter this setting screen, you can move through the digits using theleft/right cursor keys and then set the frequency using the MODIFY knob andup/down keys.
This soft key is displayed when INT OSC or SIGNAL is selected as the reference
signal.
Also, When the detection mode is DUAL2 and the reference signal is INT OSC or
SIGNAL, when the detection mode is CASCADE, this soft key is displayed as [ PRI
FREQ> ].
{Frequency Setting Screen}

The frequency for the internal oscillator can be set. The setting range varies
depending on the input signal connector.
・A, A-B, C *1, I connectors: 0.3 Hz to 3.2 MHz(6-digit resolution, 0.1 mHz for 100 Hz or less)1*
・HF connector: 8 kHz to 11.5 MHz (6-digit resolution)
FREQp is displayed in the normal measurement screen and Fp is displayed in the finemeasurement screen.
[ ×10 ] : Move Decimal Point to Right for Frequency
You can move the decimal point in the frequency setting to the right.
[ ÷10 ] : Move Decimal Point to Left for Frequency
You can move the decimal point in the frequency setting to the left.
[ SEC FREQ> ] : {Secondary Frequency Setting Screen}
The setting screen for the internal oscillation frequency (secondary PSD) is displayed.
When the detection mode is DUAL2, this soft key is displayed when the detection
mode is CASCADE and the reference signal is INT OSC.
The frequency for the internal oscillator can be set. The setting range varies
depending on the input signal connector.
・A, A-B, C *1, I connectors: 0.3 Hz to 3.2 MHz(6-digit resolution, 0.1 mHz for 100 Hz or less)1*
・HF connector: 8 kHz to 11.5 MHz (6-digit resolution)
FREQs is displayed in the normal measurement screen and Fs is displayed in the finemeasurement screen.
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LI 5655 / LI 5660

3.6 Operation Screen Reference[ ×10 ] : Move Decimal Point to Right for Frequency
You can move the decimal point in the frequency setting to the right.
[ ÷10 ] : Move Decimal Point to Left for Frequency
You can move the decimal point in the frequency setting to the left.
[ AMPTD> ] : {Amplitude Setting Screen}{Amplitude Setting Screen} for the sine wave output (OSC OUT) is displayed.
When you enter this setting screen, you can move through the digits using theleft/right cursor keys and then set the amplitude value using the MODIFY knob andup/down keys.
{Amplitude Setting Screen}[ AMPTD ] : Amplitude Setting
The amplitude value can be set.
[ ×10 ] : Move Decimal Point to Right for Amplitude ValueYou can move the decimal point for the amplitude setting value to the right.
[ ÷10 ] : Move Decimal Point to Left for Amplitude ValueYou can move the decimal point for the amplitude setting value to the left.
[ RANGE ] : Amplitude Range Setting
The amplitude range for the sine wave output can be set.
Range
Amplitude
range
Resolution

10 mV

100 mV

1V

0 to 10.00 mVrms

0 to 10.00 mVrms

0 to 1.000 Vrms

0.01 mVrms

0.1 mVrms

0.001 Vrms

In the case of input connector HF *1, the output is 0 Vrms regardless of the setting.
If the frequency exceeds 3.2 MHz, the output is 0 Vrms regardless of the setting.
■ Setting the Amplitude Value to 0 Vrms
If the amplitude value is set to 0 Vrms using the MODIFY knob and up/down keys, the clock forthe sine wave source D/A converter is stopped.
Noise in the device is reduced so very small signal measurement is more immune to disturbance.
[ SEL CH> ] : {OSC Output Oscillator Selection Screen}
Displayed when DUAL2 / CASCADE is selected for the detection mode.
The internal oscillator {PRI｜SEC} to output the sine wave can be selected.
・ PRI: Outputs the FREQp frequency of the oscillator in the primary PSD.
・ SEC : Outputs the FREQs frequency of the oscillator in the secondary PSD.

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LI 5655 / LI 5660

3.6 Operation Screen Reference[ 10MHz IN> ] : {External 10 MHz Setting Screen}{ON｜OFF} for 10MHz IN on the rear panel can be selected.
A signal generator and other devices and the LI 5655 / LI 5660 can be synchronized withthe common 10 MHz frequency source. For details,  "5.4 External 10 MHz
Synchronization"[ HMNC> ] : {Harmonic Setting Screen}
Displayed when SINGLE / DUAL1 is selected for the detection mode.
Pressing this soft key switches to {Harmonic Setting Screen}.
When you enter this setting screen, you can set ON or OFF for the setting (primary PSD)
using the MODIFY knob and up/down keys.
{Harmonic Setting Screen}《SINGLE》《DUAL1》[ ON | OFF ] : Harmonic ON / OFF{ON｜OFF} can be selected for the harmonic setting (primary PSD).
If DUAL1 is selected for the detection mode, [ PRI HMNC ON｜OFF ] is displayed.
[ n ] : n-order Harmonic Setting
An n-fold harmonic {n: 1 to 63} for the reference signal can be set.
If DUAL1 is selected for the detection mode, [ PRI n ] is displayed.
[ m ] : 1/m Fractional Harmonic
A 1/m-fold subharmonic {m: 1 to 63} for the reference signal can be set.
Fractional harmonic (n/m-fold) can be set by combining the harmonic andsubharmonic.
If DUAL1 is selected for the detection mode, [ PRI m ] is displayed.
[ SEC HMNC ] : Secondary PSD Harmonic ON / OFF
Displayed when DUAL1 is selected for the detection mode.
{ON｜OFF} can be selected for the harmonic setting (secondary PSD).
[ SEC n ] : n-order Harmonic Setting (Secondary PSD)
Displayed when DUAL1 is selected for the detection mode.
An n-fold harmonic {n: 1 to 63} for the reference signal (secondary PSD) can be set.

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LI 5655 / LI 5660

3.6 Operation Screen Reference[ DET MODE> ] : {Detection Mode Setting Screen}
Pressing this soft key switches to {Detection Mode Setting Screen}.
When you enter this setting screen, you can select the detection mode using the MODIFY
knob and up/down keys.
{Detection Mode Setting Screen}

The LI 5655 / LI 5660 are equipped with two dual-phase PSDs.
The detection mode can be selected from {SINGLE｜DUAL1｜DUAL2｜CASCADE}.
Detection mode
SINGLE
Normal mode
DUAL1
Fractional harmonic
mode
DUAL2
Independent frequency
mode
CASCADE
Cascade mode

Function description
Measures the signal components of a normal single frequency,
fundamental wave (1F), and fractional harmonic (nF/m).
Simultaneously measures the signal components of a fractional
harmonic (nF/m) using the primary PSD and those of a harmonic (nF)
using the secondary PSD.
Simultaneously measures the signal components of a primary
frequency using the primary PSD and those of a secondary frequency
using the secondary PSD.
Detects a primary frequency signal using the primary PSD and detectsthat result with a secondary frequency using the secondary PSD.

[ Exec ] : Execute Detection Mode Setting
Executes the selected detection mode.
[Cancel ] : Cancel Detection Mode Setting
Returns to the reference signal setting screen without executing the selected detection
mode.

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LI 5655 / LI 5660

3.6 Operation Screen Reference

3.6.8 AUX : {Auxiliary I/O Setting Screen}{Auxiliary I/O Setting Screen}[ AUX IN> ]: {Auxiliary Input Setting Screen}
Pressing this soft key switches to {Auxiliary Input Setting Screen}.
{Auxiliary Input Setting Screen}[ IN1 ] : Select AUX IN1 Smoothing Time Constant
The smoothing time constant for auxiliary input AUX IN1 can be selected from {THRU｜125 μs｜500 μs｜2000 μs}.
[ IN2 ] : Select AUX IN2 Smoothing Time Constant
The smoothing time constant for auxiliary input AUX IN2 can be selected from {THRU｜12 5μs｜500 μs｜2000 μs}.

3-53

LI 5655 / LI 5660

3.6 Operation Screen Reference[ INPUT> ]: {AUX IN ON / OFF Screen}
Pressing this soft key switches to {AUX IN ON / OFF Screen}.
{AUX IN ON / OFF Screen}[AUX IN1 ON | OFF] : AUX IN1 ON / OFF{ON｜OFF} can be selected for the auxiliary input AUX IN1 measurement function.
[AUX IN2 ON | OFF] : AUX IN2 ON / OFF{ON｜OFF} can be selected for the auxiliary input AUX IN2 measurement function.
■ Stopping the AUX IN Input Function
When the AUX IN measurement function is set to OFF, the clock for the internal A/D converter
stops. Noise in the device is reduced so very small signal measurement is more immune todisturbance.
[ AUX OUT> ] : {Auxiliary Output Setting Screen}
Pressing this soft key switches to {Auxiliary Output Setting Screen}.
{Auxiliary Output Setting Screen}[ OUT1 ] : AUX OUT1 Voltage Setting
The set DC voltage {-10.500 V to +10.500 V, 0.001 V resolution} can be output to theauxiliary output AUX OUT1.
[ OUT2 ] : AUX OUT2 Voltage Setting
The set DC voltage {-10.500 V to +10.500 V, 0.001 V resolution} can be output to theauxiliary output AUX OUT2.

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LI 5655 / LI 5660

3.6 Operation Screen Reference

3.6.9 UTIL : {Utility Screen}{Utility Screen}[ RESET> ] : {Reset Screen}
Pressing this soft key switches to {Reset Screen}.
{Reset Screen}[ Exec ] : Execute Reset
Executes a reset.
[ Cancel ] : Cancel Reset
Returns to the utility screen without executing a reset.

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LI 5655 / LI 5660

3.6 Operation Screen Reference[_MEMORY>_]: {Setting Memory Screen}
Pressing this soft key switches to {Setting Memory Screen}.
When you enter this setting screen, you can select the memory number using the
MODIFY knob and up/down keys.
{Setting Memory Screen}[ MEM No. ] : {Select Setting Memory}
The setting memory number for saving the setting to the device memory, recalling it,
and clearing it can be specified.
[ NAME ] : Change Setting Memory Name
The setting memory name can be edited.
Up to 8 characters can be selected from {Blank, A to Z, a to z, 0 to 9, #, @, - } andspecified for the string.
[_RECALL>_] : {Setting Memory Recall Screen}
Pressing this soft key switches to the setting memory recall confirmation screen.
[ Exec ] : Execute Setting Memory Recall
Executes the setting recall from the selected setting memory.
[ Cancel ] : Cancel Recall
Returns to the setting memory screen without executing setting recall.
[_SAVE>_] : {Setting Memory Save Screen}
Pressing this soft key switches to the setting memory save confirmation screen.
[ Exec ] : Execute Setting Memory Save
Executes the setting save for the selected setting memory.
[ Cancel ] : Cancel Save
Returns to the setting memory screen without executing the saving of settings.
[_CLEAR>_] : {Setting Memory Clear Screen}
Pressing this soft key switches to the setting memory clear screen.
[ Exec ] : Execute Setting Memory Clear Individually
Executes the selected setting memory clear (delete).
[ Cancel ] : Cancel Setting Memory Clear
Returns to the setting memory screen without executing clear.

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LI 5655 / LI 5660

3.6 Operation Screen Reference[ INTERFACE> ] : {Interface Setting Screen}
Pressing this soft key switches to {Interface Setting Screen}.
For details,  " LI 5655 / LI 5660 Instruction Manual (Remote Control)"{Interface Setting Screen}[ USB> ] : {USB Information Screen}
Pressing this soft key switches to {USB Information Screen}.
There is no setting for USB, but the vendor ID, product ID, and serial number are displayed in thesetting screen.
{USB Information Screen}[ Exec ] : Execute USB Communication Selection
Selects USB for the interface.
[ GPIB> ] : {GPIB Setting Screen}
Pressing this soft key switches to {GPIB Setting Screen}.
When you enter this setting screen, you can move through the digits using theleft/right cursor keys and then set the GPIB address {0 to 30} using the MODIFY knob
and up/down keys.
{GPIB Setting Screen}[ Exec ] : Execute GPIB Communication Selection
Confirms the GPIB address and selects GPIB for the interface.
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LI 5655 / LI 5660

3.6 Operation Screen Reference[ RS232> ] : {RS232 Setting Screen}
Pressing this soft key switches to {RS232 Setting Screen}.
When you enter this setting screen, you can set the baud rate using the MODIFY knob
and up/down keys.
{RS232 Setting Screen}[ BAUD RATE ] : Baud Rate Setting
Baud rate {4800｜9600｜19200｜38400｜57600｜115200｜230400[bps]} can be set.
[ FLOW CONTROL ] : Flow Control Setting
Flow control {NONE｜SOFT｜HARD} can be set.
・ NONE: No handshake・ SOFT: Software handshake (X-ON/X-OFF)・ HARD: Hardware handshake (RTS, CTS)

[ TERMINATOR ] : Terminator Setting
Terminator {LF｜CRLF} can be set.
・ LF

: Terminator is one character of LF (Line Feed).

・ CRLF: Terminator is two characters of CR (Carriage Return) and LF.

[ Exec ]: Execute RS232 Communication Selection
Confirms various settings and selects RS232 for the interface.

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LI 5655 / LI 5660

3.6 Operation Screen Reference[ LAN> ] : {LAN Setting Screen}
Pressing this soft key switches to {LAN Setting Screen}.
{LAN Setting Screen}[ MANUAL> ] : {Address Manual Setting Screen}
Pressing this soft key switches to {Address Manual Setting Screen}.
When you enter this setting screen, you can move through the digits using theleft/right cursor keys and then set the IP address using the MODIFY knob andup/down keys.

{Address Manual Setting Screen}[ IP ADDR ] : IP Address Setting
The IP address can be set.
[ MASK ] : Subnet Mask Setting
The subnet mask can be set.
[ GATEWAY ] : Default Gateway Setting
The default gateway can be set.
[ DNS ] : DNS Setting
The DNS can be set.
[ Exec ] : Execute LAN Communication Selection
Confirms various settings and selects LAN for the interface.
In this case, the device operates with the static addresses set above.

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LI 5655 / LI 5660

3.6 Operation Screen Reference[ AUTO>] : {Address Auto Setting Screen}
Pressing this soft key switches to {Address Auto Setting Screen}.
(Firmware version 1.50 or later){Address Auto Setting Screen}[ Exec ] : Execute LAN Communication Selection
Confirms various settings and selects LAN for the interface.
In this case, the device operates with the dynamic addresses that are assigned by using DHCP
and APIPA (Automatic Private IP Addressing).
[ RESET>] : {LAN Reset Screen}
Pressing this soft key switches to {LAN Reset Screen}.
(Firmware version 1.50 or later){LAN Reset Screen}[ Exec ] : Reset LAN Settings
Reset LAN settings and select LAN communication with auto setting.
[ Cancel ] : Cancel Resetting
Return to {LAN Setting Screen}.

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LI 5655 / LI 5660

3.6 Operation Screen Reference[ SYSTEM> ] : {System Setting Screen}
Pressing this soft key switches to {System Setting Screen}.
This is a screen for the maintenance and management of the LI 5655 / LI 5660.
{System Setting Screen}[ VERSION> ] : {Version Information Screen}
Pressing this soft key displays {Version Information Screen} of the device.
{Version Information Screen}

Displays the firmware version and last adjustment date and time.
[ SELF TEST> ] : {Self-Diagnosis Screen}
Pressing this soft key switches to {Self-Diagnosis Screen}.
An external connection, etc. is required for the self-diagnosis. For details,  "8.5.1 Self
Test"
{Self-Diagnosis Screen}[ Exec ] : Execute Self-Diagnosis
Executes the self-diagnosis.
[ Cancel ] : Cancel Self-Diagnosis
Stops the self-diagnosis and returns to the system setting screen.
3-61

LI 5655 / LI 5660

3.6 Operation Screen Reference

Operation Message
The process ("Executing...") is displayed during the execution.
When the execution is completed successfully, "Done" is displayed for a short time.
If there is a problem, an error message and "Error" are displayed. In this case, thescreen does not return to the original measurement screen but remains unchanged.
If the execution is stopped or interrupted, "Canceled" is displayed and the screen
returns to the original measurements screen.

[ SERVICE> ] : {Maintenance Information Screen}
Pressing this soft key displays {Maintenance Information Screen} of the device.
The operating time (in minutes) and power on count are displayed.
{Maintenance Information Screen}[ INIT> ] : {Initialize Execution Screen}
Pressing this soft key displays {Initialize Execution Screen}.
Initialize restores the factory default state.
{Initialize Execution Screen}[ Exec ] : Execute Initialize
Executes the initialize operation.
[ Cancel ] : Cancel Initialize
Returns to the utility screen without executing the initialize operation.

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LI 5655 / LI 5660

3.7 Initial Settings

3.7 Initial Settings
The settings of the LI 5655 / LI 5660 are the initial settings in the following cases.
 At the Time of Shipment from the Factory
All the settings are the initial settings. The setting memory is empty.
When [SYSTEM>]-[INIT>] is executed from UTIL : {Utility Screen}, the settings are reset to thefactory default settings.
However, the maintenance information is not changed.
 When Executing the Reset Command
Resets settings other than the setting memory, power supply frequency, interface, and key lock settings
to the initial settings.
Panel Operation
In UTIL : {Utility Screen}, press the soft key in order of [RESET] and [Exec].
Remote Control Command* RST command When Executing the System Reset Command
Resets all settings except for the interface setting to the initial settings.
Remote Control Command:SYSTem:RST, If there is an error with the resume memory where the last settings are stored when the
power is turned on
The part with the error is reset to the initial state.
(If all is normal, the last settings are restored)
For details on the initial setting items and content,  "Table 3-1 Setting Items and Initial Values"
Table 3-1 shows also the relationship of the auto setting function, setting memory, and resume witheach parameter.
*1: Only the LI 5660 is equipped with the C and HF inputs.

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LI 5655 / LI 5660

3.7 Initial Settings:SYST:RST*RST

AUTO MEAS

SettingmemoryResumeTable 3-1 Setting Items and Initial Values 1/4

NORMal|LARGe|FINE

NORM





N

Y

Y

X|R|AUX 1|NOIS

R
R










Y
Y

Y
Y







Y

Y










Y
Y

Y
Y







Y

Y










Y
Y

Y
Y

Setting item

<Measurement Screen><Measured Data>
DATA1
SINGLE
DUAL1
DUAL2
CASCADEDATA2
SINGLE
DUAL1
DUAL2
CASCADEDATA3
SINGLE
DUAL1
DUAL2
CASCADEDATA4SINGLE
DUAL1
DUAL2
CASCADEDATA OUTPUT
DATA1
DATA2
DATA3
DATA4

<Noise Smoothing Factor><Offset>X Offset
ON / OFFRange
Y Offset
ON / OFF
Range<Arithmetic Function><EXPAND Scale Factor>
X / R EXPAND Scale Factor
Y EXPAND Scale Factor

Parameter range

Xp|Rp|Yp|θp|Xs|Rs|AUX 1|NOIS

Initial value(SINGLE)Rp

Y|θ|AUX1|AUX2

θθ

(SINGLE)

Yp|θp|Xs|Rs|Ys|θs |AUX1|AUX2

θp

X|R

X
X

Xp|Rp|Yp|θp|Xs|Rs

Xp







Y

Y

Y|θ

Y (SINGLE)
Y










Y
Y

Y
Y

Yp|θp|Xs|Rs|Ys|θs

Yp







Y

Y

ON|OFF
ON|OFF
ON|OFF
ON|OFF
1|4|16|64

ON
ON
ON
ON
1







Y

Y





N

Y

Y

(SINGLE)(Primary / Secondary PSD,
Standalone)
OFF|ON±105.000 %

OFF
0%










Y
Y

Y
Y

OFF|ON±105.000 %OFF|EXPAND|NORM|RATIO(Primary / Secondary PSD,
Standalone)
1|10|100
1|10|100

OFF
0%











N

Y
Y
Y

Y
Y
Y

1
1










Y
Y

Y
Y

% |dB|%FS

%







Y

Y

1 nV to 10 V
1 fA to 1 μA
Up to 3 characters (specified
character types)

1V
1 μA










Y
Y

Y
Y

Blank







Y

Y

OFF

<Normalize>
Display Form
Standard ValueV
I
User Unit

3-64

LI 5655 / LI 5660

3.7 Initial Settings*RST

AUTO MEAS

SettingmemoryResumeSetting item

:SYST:RST

Table 3-1 Setting Items and Initial Values 2/4







Y

Y

1







Y

Y

1V
(1 V)
(1 μA)(10 nA)
(1 V)





A

Y

Y

OFF







Y

Y

LOW





A

Y

Y

100 ms
24 dB/oct
TC









A

A

Y
Y
Y

Y
Y
Y

AUTO
200 ms
Factory default value










N
N

Y
Y
Y

Y
Y
Y

A





N

Y

Y

1M





A

Y

Y

AC
GROUND
1 MΩ









A
N
N

Y
Y
Y

Y
Y
Y

Parameter range

Initial value<Ratio Arithmetic
Expression>
SINGLE
DUAL1
DUAL2
CASCADE
Ratio Scale Factor K<Sensitivity>
1

Sensitivity *Always Auto Selection<Dynamic Reserve><Time Constant Filter>
Time ConstantAttenuation Slope
Filter Type

<PSD Input Offset>
PSD Continuous Auto
Adjustment Settling Time
Adjustment ValueRATIO1RATIO1|RATIO2RATIO1|RATIO2RATIO10.10000 to 10.0000(Primary / Secondary PSD,
Standalone)
A, A-B
10 nV to 1 V
C
1 mV to 10 V
I（1M） 100 fA to 1 μA
I（100M）10 fA to 10 nA
HF 1 mV to 1 V（1-2-5）
OFF|ONRATIO1

HIGH|MED|LOW(Primary / Secondary PSD,
Standalone)
1 μs to 50 ks（1-2-5）
6|12|18|24 dB/oct
TC | SYNC(Primary / Secondary PSD,
Common)HOLD|AUTO
200 ms|750 ms|3000 ms
Not disclosed<Signal Input>
1
A|A-B|C|I|HF
Input Connector *Current to Voltage Conversion
1 M|100 M
Gain
Input Coupling
AC|DC
Signal Ground
FLOAT|GROUND
1*
1 MΩ50 Ω
HF Input Impedance<Signal Filter>
Line Filter

THRU|L1|L2|L1&L2
L1 is 50 Hz or 60 Hz
L2 is 100 Hz or 120 Hz

THRU (OFF)







Y

Y

Line Frequency

50|60 Hz50 Hz
(factory default)

N

N

N

N

W

0°
SINGLE








N

Y
Y

Y
Y

REF IN





N

Y

Y

SIN+





N

Y

Y

<Phase Adjustment>
Phase Shift Amount<Detection Mode>(Primary / Secondary PSD,
Standalone)-180.000 to +179.999°
SINGLE|DUAL1|DUAL2|CASCADE<Reference Signal>
Reference Signal Source

Waveform(REFERENCE INPUT)REF IN |INT OSC |SIGNAL
SIN+|TTL+|TTL-

3-65

LI 5655 / LI 5660

3.7 Initial Settings

SettingmemoryResume

Y

Y

N

Y

Y

Y

Y

10.0000 kHz
1.00000 kHz    N
 
 
N
 
N

Y
Y

Y
Y

1 Vrms0.000 Vrms
PRI
OFF











N
N
N
N

Y
Y
Y
Y

Y
Y
Y
Y

OFF|ON
OFF|ON
1 to 63
1 to 63
1 to 63

OFF
OFF
1
1
1





N

Y

Y





N

Y

Y

THRU|125 μs |500 μs |2000 μs
THRU|125 μs |500 μs |2000 μs

2000 μs
2000 μs







N
N

Y
Y

Y
Y

ON|OFF
ON|OFF

ON
ON










Y
Y

Y
Y

±10.5000 V±10.5000 V
OFF|ON

0V
0V
OFF (Cancellation)







N
N

Y
Y

Y
Y



N

N

N

N

OFF|ONON (Lit)



N

N

N

N

<Data Transfer Format>

ASCII|real number|integer

ASCII





N

N

N

Measured Data Set(for query)

STATUS, DATA1, DATA2，
DATA3, DATA4, FREQDATA1＋DATA2





N

N

N

STATUS, DATA1, DATA2，
DATA3, DATA4, FREQ
Send|Not send

DATA1＋DATA2





N

N

N

Not send







N

N

(Unit: Sample point)
16 to 8192
16 to 65536(Maximum value)
8192
65536





N

N

N

Parameter range

Initial value

*RST

N

Setting item

:SYST:RST

AUTO MEAS

Table 3-1 Setting Items and Initial Values 3/4<Internal Oscillator>
1
Detection mode {SINGLE,
Frequency *DUAL1, DUAL2}
A, A-B, C, and I inputs
for both the primary and0.3000 Hz to 3.20000 MHz
secondary frequencies
HF inputfor both the primary and 8 kHz to 11.5000 MHz
secondary frequencies
1
Detection mode CASCADE
Frequency *A, A-B, C, and I inputs
for both the primary and 0.3000 Hz to 3.20000 MHz
secondary frequencies
8.00000 kHz to 11.5000 MHz
HF input
0.3000 Hz to 3.20000 MHz
Primary frequency
Secondary frequency
Output Voltage Range
10 m|100 m|1 Vrms
Output Voltage (Amplitude)
0.00 m to 1.000 Vrms
Output Selection
PRI|SEC
10MHz In
OFF|ON

1.00000 kHz
10.0000 kHz

1.00000 kHz

 
 
 
 
 
 

<Harmonic>
Primary PSD
Secondary PSD
Primary PSD-n
Primary PSD-m
Secondary PSD-n<Auxiliary Input>
AUX IN 1 Time Constant
AUX IN 2 Time Constant

AUX INPUTAUX IN 1
AUX IN 2<Auxiliary Output>
AUX OUT 1 Range
AUX OUT 2 Range<Key Lock><Lamp Control><Measured Data Buffer>
Measured Data Set(for recording)
FEED:CONTrol
BUF1, BUF2, BUF3
Buffer Size
BUF1, BUF2, BUF3

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3.7 Initial Settings:SYST:RST*RST

AUTO MEAS

SettingmemoryResumeTable 3-1 Setting Items and Initial Values 4/4

Trigger Source
Trigger Delay Time

MAN|EXT|BUS
0 to 100 s 640 ns ×N

BUS
0s







N
N

Y
Y

Y
Y

Timer Function

ON|OFF

OFF





N

Y

Y

Timer Period

1.92E-6 to 20 s 640 ns ×N

10 ms





N

Y

Y

USB|GPIB|RS232|LAN
0 to 304800 to 230400
LF|CR LF
NONE|SOFT|HARD
0.0.0.0 to 255.255.255.255
0.0.0.0 to 255.255.255.255
0.0.0.0 to 255.255.255.255
0.0.0.0 to 255.255.255.255

USB
2
9600
CR LF
NONE
192.168.0.2
255.255.255.0
0.0.0.0
0.0.0.0

N
N
N
N
N
N
N
N
N

N
N
N
N
N
N
N
N
N

N
N
N
N
N
N
N
N
N

N
N
N
N
N
N
N
N
N

W
W
W
W
W
W
W
W
W

—

Initial value



N

N

—

W

Setting item

Parameter range

Initial value<Trigger><Interface>Type
GPIB Address
RS-232 Baud Rate
RS-232 Flow Control
RS-232 Terminate
LAN IP Address
LAN Subnet Mask
LAN Default Gateway
LAN DNS<Setting Memory>
Content■ Remark
Initial value At the time of shipment from the factory:SYST:RST Remote control when executing the :SYSTem:RST command*RST

Remote control when executing the *RST command
The UTIL [ RESET ] operation is the same as the *RST command,
except that the :INIT:CONT system is not influenced.

Same as on left (initial value)

Refer to aboveA

Depending on the auto setting function (the result varies depending on the situation)

N

There is no function (no influence)Y

There is the function

W

There is the function However, data is held independently from the general resume
objects.
Set by remote control / cannot be queried.

－

Not applicable

The following is not covered by the scope of resume.
・ Measurement data stored in the measurement data buffer・ Latest measurement data
・ Sensitivity and dynamic reserve selected in Continuous Auto Setting

3-67

LI 5655 / LI 5660

3.7 Initial Settings(Blank)3-68

LI 5655 / LI 5660

4． Basic Operations

4.1 Display and Operation when Power Is Turned On ............... 4-3
4.1.1 Check before Turning On the Power ........................................ 4-3
4.1.2 Startup Screen and Operation on Startup ................................. 4-3

4.2 Simple Operation Procedure for Using the Device
for the First Time ................................................................... 4-4
4.3 Measurement Parameter Setting, Output, and Display ........ 4-8
4.4 Reference Signal Setting and Connection .......................... 4-11
4.5 Input Connector Setting and Connection ............................ 4-15
4.6 Time Constant Filter Setting and Characteristics ...............4-23
4.6.1 How to Set the Filter ............................................................... 4-23
4.6.2 Time Constant Filter Characteristics ....................................... 4-24
4.6.3 Auto Setting of Time Constant ................................................ 4-27

4.7 Sensitivity and Dynamic Reserve Setting ........................... 4-28
4.7.1 How to Set the Sensitivity ....................................................... 4-28
4.7.2 Sensitivity and Dynamic Reserve Auto Setting ....................... 4-30
4.7.3 Signal Over-level Display and Monitor Output ........................ 4-31

4.8 Phase Adjustment ............................................................... 4-33

4-1

LI 5655 / LI 5660

3.7 Initial Settings

This chapter describes the basic operations for the normal single frequency and dual-phase detection.
For details on advanced usage,  "5．Advanced Operations"
For details on dual frequency measurement,  "6．Dual Frequency Measurement"

4-2

LI 5655 / LI 5660

4.1 Display and Operation when Power Is Turned On

4.1 Display and Operation when Power Is Turned On
4.1.1 Check before Turning On the Power
Before setting the power switch to ON, see "2.3 Grounding and Connecting to Power Outlet" andcheck that the device is grounded and the setting of the power voltage selector switch is appropriate.

4.1.2 Startup Screen and Operation on Startup
When the power switch is set to ON, the startup screen is displayed. Furthermore, all lamps are lit for the
first several seconds to check operation.  "3.7 Initial Settings"

During this period, the internal initial settings are
configured and self-diagnosis is performed. If an error is
detected, an error message is displayed.
If a critical error is detected, an error message is displayedand operation becomes no longer possible.

Startup Screen
If the last settings are lost, an error message is displayed,
but the error parameter is reset and the startup screen isdisplayed. This error message can be cleared by pressing
any key.
For details,  7.1.1 Power-On Errors.
For details on the reset information,

 "3.7 Initial Settings"
Error Message at Startup(for Reference)

If there is no error with the resume memory where the lastsettings are stored, the settings when the power was
turned off last are restored.
When the device starts up normally, a message isdisplayedforseveralseconds

and

then

the

measurement screen is displayed.
For details,  "3.4 Overview of the Operation
Screen".
After this point, measurement and panel operations are
possible.
Message at Normal Startup

It takes about 30 seconds from startup before the remote control function can be used. During this period,
the REMOTE lamp flashes, but setting and measurement operations can be performed using the operation
keys.

4-3

LI 5655 / LI 5660

4.2 Simple Operation Procedure for Using the Device for the First Time

4.2 Simple Operation Procedure for Using the Device for the First Time
If a proper reference signal is obtained for the sine wave or square wave (duty about 50%), a measurement
can be performed using the following simple procedure.
 Reset ( ＿UTIL＿  [ RESET> ]  [ Exec ] ) Connect the measured signal ( A) and reference signal ( REF IN)
 Auto setting ( ＿AUTO＿  [ MEASURE ] )At the measurement screen
 Manual adjustment (Sensitivity:

Time constant:） Select the measurement data ( / DATA key: Select from R-θ or X-Y)
1) Reset Press the ＿ UTIL＿ key to display the {Utility Screen}.
 Press the [ RESET> ] soft key and then the [ Exec ] soft key in the lower-levelscreen.
The reset operation can be canceled using the [ Cancel ] soft key.
You can return to the upper-level operation screen or measurement screen using the＿SCRN＿ / EXIT key.
The above reset operation results in the following settings.
Signal input connector

A (single-ended)

Input coupling

AC

Reference signal source

REF IN, SIN+ (Phase reference: Sine wave rise zero cross point)

Detection mode

SINGLE (single frequency measurement)

Harmonic

1/1 (fundamental wave measurement)

Measurement screen

Normal (displays the measured value, bar graph, and main settings)

Measurement data

DATA1 - DATA2: R - θ (signal magnitude - phase)
Operation screen[ RESET> ](Simple operation keys) selection keys

{Utility Screen}

Soft keys

4-4

SCRN / EXIT key

UTIL key

LI 5655 / LI 5660

4.2 Simple Operation Procedure for Using the Device for the First Time

2) Connecting the Measured Signal and Reference Signal
Connect both the measured signal and reference signal prior to "3) Auto Setting." To use a lock-in
amplifier, in general, a reference signal serving as a reference for the frequency and phase is required.

A

REF IN

Measured signal

Reference signal

The following specifications are used for this explanation.
Measured signal: Single-ended, and noise is at the level where the waveform can be
identified
External reference signal: Sine wave or square wave (duty ≒ 50%) of order of several
Vp-p
Other signal input connectors and other reference signals are selected in each setting screen andoperation screen.
Go to another operation screen
For details on signal input,
For details on reference signal, 



SIG

REF

key

key

Return to the measurement screen: ＿SCRN＿ / EXIT key
3) Auto Setting
 To perform auto setting, press ＿AUTO＿ key to {Auto Setting Screen}, and then press
the [MEASURE] soft key.
This performs auto setting in the following order.
a) Time constant filter (time constant and attenuation slope)
Performs auto setting according to the frequency of the reference signal.
b) Sensitivity (signal full scale) and dynamic reserve
It takes time because the adjustment is performed one step at a time according to thesignal and noise levels.
c) Phase (phase shift amount of the reference signal)
Adjusts the phase shift amount so the Y output and θ output become zero.
At this point, the X output becomes equal to signal magnitude R. This X output has theadvantage that it is more immune to the random noise than the R output.
When the auto setting is completed, the screen returns to the measurement screen.

4-5

LI 5655 / LI 5660

4.2 Simple Operation Procedure for Using the Device for the First Time

4) Manual Adjustment
If the measurement fails in the auto setting, use the manual adjustment.
The following parameters can be adjusted also in the measurement screen.
Sensitivity (SENS)
Can be selected with the up/down keys.
Select the sensitivity so the measured value becomes close to the full scale without exceeding thespecified level (over-level). If saturation occurs anywhere in the signal path inside the device, an
icon (red) for INPUT, OUTPUT, etc. is displayed in the status area at the top of the screen. A correct
value cannot be obtained in this state.
Time Constant (TC)Can be selected with the left/right cursor keys.
If the measured value fluctuates due to noise, increase the time constant.
Up/down keys
MODIFY knob

Left/right cursor keys

5) Select the measurement data
In the measurement screen, the value in DATA1 and DATA2 can be selected from R-θ and X-Y using
the  / DATA key.
Output connector

Measurement
parameter

Measured value

Input connector
Input coupling

DATA1

Signal ground

DATA2

Sensitivity
Dynamic reserve
Time constantSine wave
amplitude

Attenuation slope

Phase shift
amountSynchronous filter
Synchronous frequency(fundamental wave)

Reference signal
setting

Note that the display can be switched to the expanded display and details display using
the ＿SCRN＿ key.
For details,  "3.3 Overview of the Measurement Screen"

4-6

LI 5655 / LI 5660

4.2 Simple Operation Procedure for Using the Device for the First Time

6) Advanced Settings
To perform other advanced settings, press the operation screen selection key to go to each operation
screen.
For details,  "3.4

Overview of the Operation Screen", "3．Panel Operation List", or"5．Advanced Operations".
When the measured value exceeds the specified level (over-level) even if it does not reach the full scale,increasing the dynamic reserve (DR) may enable measurement to be performed successfully.
For details,

 "4.7 Sensitivity and Dynamic Reserve Setting"

When you have confirmed that the measured value has sufficiently stabilized, press the [PHASE] soft
key in the ＿AUTO＿ key: {Auto Setting Screen} so that you can adjust the phase correctly (θ = 0，
Y = 0).
For details on manual adjustment,



PHASE

key: {Phase Adjustment Screen} "4.8 Phase Adjustment"

4-7

LI 5655 / LI 5660

4.3 Measurement Parameter Setting, Output, and Display

4.3 Measurement Parameter Setting, Output, and Display
The following shows how to specify the measurement parameters to output and display in DATA1 to
DATA4.

DATA key(Operation screen selection
key)
 / DATA key(Simple operation key)1) Operation in the Measurement Screen
Any of the following can be set only in DATA1 and DATA2 using the  / DATA key.
DATA1 - DATA2: R-θ or X-Y (which are sequentially switched)2) Operation in the Operation ScreenFirst press the ＿DATA＿ key to go to the following {Output Signal Selection Screen}.
For details on the output signal settings,  "3.6.2

DATA : {Output Signal Setting Screen}"{Output Signal Setting Screen}

Current DATA 1, DATA2, DATA3, and DATA4 Output / Display Parameters{Basic Measurement Parameter Setting Screen}

Next, press the [ BASIC> ] soft key to go to the{Basic Measurement Parameter Setting Screen},
where the basic combination soft key is displayed.
The soft key display content is specified in DATA1
and DATA2.
Press the [ X-Y ] soft key to set X in DATA1 and Y
in DATA2.
DATA3 and DATA4 are not changed.

4-8

LI 5655 / LI 5660

4.3 Measurement Parameter Setting, Output, and Display{Custom Measurement Parameter Setting Screen}
Press the [ CUSTOM> ] soft key to go to the{Custom Measurement Parameter Setting Screen},
where any measurement parameter can be set in
DATA1 to DATA4.
To change the parameter in DATA1, press the[ DATA1 ] soft key to select the measurement
parameter using the MODIFY knob or up/down
Setting range

Current setting

keys.

If NOISE (noise density) is specified in DATA1, the [ NOISE ] soft key is displayed in the{Output Signal Selection Screen}, where the smoothing factor can be set.
For details on NOISE (noise density),  "5.6

Noise Density Measurement"

The following shows the meaning of each parameter.
Parameter
Description
In-phase component (=R cos θ)XQuadrature component (=R sin θ)YRSignal magnitude (= X2  Y 2 )
θ
AUX1，
AUX2
NOISE

SignalY
R

Signal phase (= tan1 Y / X )θ
XDC input voltage (rear panel)
PSD reference signal

Noise density

Values in DATA1 to DATA4 are displayed both in the measurement screen and operation screen.
Values and bar graphs in DATA1 and DATA2 are displayed in the Normal measurement screen andLarge measurement screen.
The following shows an example of the Normal measurement screen{Normal Measurement Screen}
DATA1
DATA2

For details on each measurement screen,  "3.3

Overview of the Measurement Screen"

4-9

LI 5655 / LI 5660

4.3 Measurement Parameter Setting, Output, and Display

Analog signals in DATA1 to DATA4 can be obtained from the corresponding DATA OUT 1 to DATAOUT 4 output connectors.

DATA OUT 1，2
DATA OUT 3，44-10

LI 5655 / LI 5660

4.4 Reference Signal Setting and Connection

4.4 Reference Signal Setting and Connection
The following shows how to specify the reference signal serving as a reference of the frequency and phase.
*1: Only the LI 5660 is equipped with the HF connector.

REF key(Operation screen selection
key)1) Select the Reference Signal SourceFirst press the ＿REF＿ key to go to the following {Reference Signal Setting Screen}.
{Reference Signal Setting Screen}

Next, press the [ SOURCE ] soft key to select thereference signal source from the following.
REF IN (External reference signal)
Input the reference signal from the REF IN
connector.
INT OSC (Internal oscillator)
Generates the specified frequency inside thedevice. (External connection is not required)Selectable parameters

SIGNAL (Measurement signal)
Internally creates a synchronous signal from ameasured signal at the A connector, etc.

SIGNALREF IN

4-11

LI 5655 / LI 5660

4.4 Reference Signal Setting and Connection

2) External Reference Signal (REF IN)
When the external reference signal is selected, the [ EDGE ] soft key is displayed.
Press the [ EDGE ] soft key to select the waveform and edge for the external reference signal.
{Reference Signal Setting Screen}

Selectable parameters

Current edge

 SIN+ : Sine wave (0.3 to 20 Vp-p, 3.2 MHz max.),
Point to go through the average value in an upward direction.
 TTL+ : Square wave (TTL level), rising edge
 TTL- : Square wave (TTL level), falling edge

REF IN waveform:

SINE

TTL POSVth
0V

0V

TTL NEGHigh 2.6 V or more
Low 0.8 V or less

Vth
0V

0°

0°

0°

■ UNLOCK
If the external reference signal (REF IN) or measurement signal (SIGNAL) is set for
the reference signal source and they are not synchronized, the UNLOCK status isdisplayed in the measurement screen.
The frequency and measured value displayed in the UNLOCK status do notcorrespond to the actual signal correctly so the values fluctuate.
If not synchronized, the frequency, magnitude, and waveform of the reference signal
are considered to be different from the settings. Furthermore, if the noise included in
the reference signal and the fluctuations of the frequency and amplitude are large,
they may not be synchronized.

4-12

LI 5655 / LI 5660

4.4 Reference Signal Setting and Connection3) Internal Oscillator (INT OSC)
{Oscillator Setting Screen}

To use the internal oscillator, press the [ OSC SET> ]soft key to go to the {Oscillator Setting Screen}.
Then set the frequency and output amplitude (for OSC
OUT) of the internal oscillator.

{Frequency Setting Screen}
OSC OUT
Press the [ FREQ> ] soft key to go to the {Frequency
Setting Screen} and set the frequency using the cursors
and MODIFY knob.
Setting range

Current setting{Amplitude Setting Screen}

Press the [ AMPTD> ] soft key to go to the {Amplitude
Setting Screen} and set the amplitude using the cursors
and MODIFY knob.
The output range (10 mVrms, 100 mVrms, 1 Vrms) canbe set using the [ RANGE ] soft key.

Setting range

REF OUT

Current setting

A sine wave at the set frequency and amplitude is output from OSC OUT on
the front panel and a square wave signal at the TTL level synchronized with
OSC OUT connector is output from REF OUT connector on the rear panel.
OSC OUTREF OUT

0V

1 Vrms max(Fixed to 0 Vrms at >3.2 MHz）

3.3 Vp-p nominal value(Fixed to the High or Low level at >3.2 MHz)
0V

If the frequency is increased, a phase shift occurs between OSC OUT and REF OUT.

4-13

LI 5655 / LI 5660

4.4 Reference Signal Setting and Connection

The amplitude for the internal oscillator output OSC OUT (sine wave) can be set regardless of thereference signal source.
The output amplitude is fixed to 0 Vrms at a frequency > 3.2 MHz regardless of the amplitude setting. At
this point, the rear panel REF OUT (square wave) signal is fixed to the high level or low level.
If the amplitude range is switched, a brief glitch (dip or peak) occurs.
If the detection mode is DUAL2 and CASCADE, and the secondary frequency is set to output, the set
frequency of the secondary frequency is output regardless of the reference signal source.
■ Restrictions (When Using the HF Connector*1)
If the HF connector is selected, the amplitude cannot be set. Furthermore, the output is 0 Vrms.
■ Crosstalk Reduction
If OSC OUT (sine wave) and REF OUT (square wave) are not in use and the amplitude for
OSC OUT is set to 0 V, the crosstalk from the reference signal to the measured signal can be
reduced.
4) Measurement Signal (SIGNAL)
To use the reference signal source as SIGNAL and synchronize it with the measured signal, first press
the [ OSC SET> ] soft key to go to the {Oscillator Setting Screen}. Next, press the [ FREQ> ] soft key
to go to the {Frequency Setting Screen} and set the frequency as close to the measured signal as possibleusing the cursors and MODIFY knob. If the frequency is far away from it, synchronization may be
impossible or may take time.
If large noise is included in the input signal, set the time constant filter properly to reduce the influenceof the noise. If stable measured values cannot be obtained, synchronization may be impossible.
■ Restrictions (When Using the HF Connector*1)
If the HF connector is selected, SIGNAL cannot be selected regardless of the measured signal
frequency.
5) Actions and Output of the Internal Oscillator
The internal oscillator acts as follows depending on the reference signal source.
Reference signal
sourceREF ININT OSC

SIGNAL

Action of the internal oscillator
Synchronized with external reference signal REF IN.
Oscillates at the frequency set by a value.
If the reference signal source is switched to another one, the internal
oscillator switches the frequency to the frequency and phase of the newreference signal source.
However, the frequency set by a value is stored. If the reference signal
source is returned to INT OSC, the previous frequency (set by a value) is
restored.
Synchronized with the measured signal (A connector, etc).

4-14

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection

4.5 Input Connector Setting and Connection
The following shows how to set the measurement signal input connector.
*1: Only the LI 5660 is equipped with the C and HF connectors.

SIG key{Input Signal Selection Screen}

1) Select the Signal Input Connector
First press the ＿SIG＿ key to go to the following {Input Connector Selection Screen}.
{Input Connector Selection Screen}
A

Voltage (1 Vrms max.)A-B Voltage (Differential, 1 Vrms max.)

Selectable parameters

C

Voltage (10 Vrms max.)*1

I

Current (1 μArms max.)HF

Voltage (10 kHz to 11 MHz, 1 Vrms max.)*1

Current input setting

Connect the cable to the selected input connector.
Do not connect an unnecessary cable to the unselected input
connector. An unnecessary signal(interference)from theunnecessary cable may be mixed into the measured signal.

SIGNAL

4-15

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection2) AA (A connector) is the most generally used input connector for single-ended voltage signal.
Voltage sensitivity: 10 nV to 1 V (RMS value of signal)

Frequency range: 0.5 Hz to 3.2 MHz

Input impedance: 10 MΩ (nominal value), 50 pF in parallel (supplementary value)

Maximum input voltage: ±3V (between signal and ground)

If the signal significantly exceeds the maximum
AC / DC

input voltage range, the input connector may temporarily
be separated from the inside for protection.

+3.8V

Protective
relay

A,B

10M

0.15u

-3.8V

■ Noise Figure (NF)
Since an amplifier generates noise inside, the S/N ratio deteriorates wherever an amplifier is used. A
noise figure indicates the extent to which the S/N ratio deteriorates. It indicates that the smaller the
NF is the better the noise performance is.
NF [dB]= output S/N ratio [dB] - input S/N ratio [dB]
100M
10 dB

6 dB

20 dB
INPUT：A
SENS：1mV
DR：LOW

3 dB

10M

Signal source resistance [Ω]1 dB
1M
0.2 dB
0.1 dB

100k

10 k
3 dB
1k
6 dB
10 dB
100
20 dB
10

100

10 k

1k

100 k

1M

Frequency [Hz]Figure 4-1 Noise Figure (Supplementary Values)
The NF varies depending on the frequency and signal source resistance. It depends on not only the
input capacity but also the cable length at a high frequency.
Furthermore, the signal source resistance at which the NF is the minimum value is called the
optimum signal source resistance. However, even if a resistor is installed in series with the signal
source resistance to achieve the optimum signal source resistance, the S/N ratio is not improved.
In particular, if noise must be low, use a proper preamplifier. Install a preamplifier as close to the signal
source as possible to reduce the influence of common-mode noise.
Ground the preamplifier close to the signal source.
4-16

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection3) A-BA-B is a differential connection between A connector and B connector. Even if there is common-mode
noise in the ground potential of the signal source and the signal reference potential of the LI 5655 /LI 5660, the influence on the measurement can be reduced. For A-B, B connector is used as a reference
to measure the voltage signal of A connector.
Voltage sensitivity: 10 nV to 1 V (RMS value of signal)

Frequency range: 0.5 Hz to 3.2 MHz

Input impedance: 10 MΩ (nominal value), 50 pF in parallel (supplementary value)

Maximum input voltage: ±3V (between signal and ground, between signal A and B)■ CMRR (Common Mode Rejection Ratio)
The capability to remove the signal (noise) component commonly added to both inputs is called
CMRR (Common Mode Rejection Ratio).
The CMRR varies depending on the sensitivity (SENS), dynamic reserve, and input coupling (AC｜DC).

Signalsource

[dB]

120
A

CMRR

B

DR:Low，SENS:20mV

DC
100
AC
80

Common-mode
noise

1

10

100
1 k 10 k 100 k
Frequency〔Hz〕

Figure 4-2 CMRR (Supplementary Values)
CMRR Deterioration Factors
・High signal source impedance and mismatch of the signal source impedance
If the signal source impedance is low enough, there is no problem. However, if the signal source
impedance is high, the mismatch of the signal source impedance between A and B causes the
CMRR to deteriorate significantly.
・Mismatch of the cable capacity
If the type and length of both signal cables vary, the capacity to ground of each signal line also
varies, so the CMRR deteriorates at a high frequency.

4-17

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection4) C *1
C (C connector) is an input connector for a single-ended voltage signal for measuring the voltage rangethat cannot be measured directly using the A connector; for example, a large output voltage signal of thepreamplifier, or large voltage signals including noise.
Voltage sensitivity: 1 mV to 10 V (RMS value of signal)

Frequency range: 0.5 Hz to 3.2 MHz

Input impedance: 1 MΩ (nominal value)C
1MΩ→ Attenuator

50 pF in parallel (supplementary value)
Maximum input voltage : ±30V (between signal to ground)

DC
Cancel■ Restrictions (When Using C)
The C connector is always the DC coupling regardless of the input coupling (AC｜DC) setting.
However, the action is almost the same as the AC coupling, because the DC component included in
the input is corrected by the DC cancel circuit.

4-18

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection5) I
I (I connector) converts a current signal to a voltage signal using a current - voltage converter andmeasures it.
If I is selected, select the current - voltage conversion gain considering the magnitude and frequency ofthe current signal.
For details on the specifications,  "9.1 Measured signal system
100b) Current measurement"

For the polarity of the current, the direction in which the current

I

flows from the I connector to the signal source is positive.

–+{Input Connector Selection Screen}

Conversion gain 1 M:
Conversion gain 106 V/ACurrent sensitivity 100 fA to 1 μA
Bandwidth 1 MHz *2
Conversion gain 100 M:
Conversion gain 108 V/ACurrent sensitivity 10 fA to 10 nA
Bandwidth 10 kHz *2

Settable parameters

Current setting*2: Cs is the capacity of the signal source (including theconnection cable)-3 dB bandwidth when Cs=150 pF (supplementary
value)For the current input, the frequency characteristic changes by Cs. Furthermore, when Cs increases, thenoise density increases at a high frequency. Depending on the sensitivity and dynamic reserve settings,
the level may be exceeded (over-level) inside the LI 5655 / LI 5660 due to the influence of noise. Adjust
the sensitivity and dynamic reserve as needed.
Furthermore, to avoid the influence of noise as much as possible, install a current input amplifier (NF
Corporation's WIDEBAND CURRENT AMPLIFIER SA-600 series, etc.) as close to the signal source-10

Conversion gain
100 M

Conversion
gain 1 M

-20

1k

10 k

100 k

1M

Frequency〔Hz〕

1000
300

〔fA/√Hz〕

0

Current noise density

Ref：DC Gain〔dB〕

as possible to convert a current to a voltage and connect it as a voltage signal to the A or C *1 input.

1M
150 fA

100
30

100 M
15 fA

10

1k

10 k

100 k

1M

Frequency〔Hz〕

Figure 4-3 I Input Frequency
Characteristics (Supplementary Values)

Figure 4-4 I Input Referred Noise Density(Supplementary Values)

4-19

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection6) HF *1
HF (HF connector) is an input connector for a single-ended voltage signal for measuring frequencies
above 3 MHz. To use the HF connector, select the input impedance (1 MΩ｜50 Ω).
Voltage sensitivity: 1 mV to 1 V (RMS value of signal)

Frequency range: 10 kHz to 11 MHz

Input impedance: 1 MΩ (nominal value), 50 pF in parallel (supplementary value),or 50 ΩMaximum input voltage : ±3V (between signal to ground){Input Connector Selection Screen}

If the frequency exceeds 1 MHz and the reflection of thesignal cannot be ignored, it is recommended to set boththe characteristic impedance of the connection cable andthe input impedance of the HF connector to 50 Ω.

Settable parameters

Current setting■ Restrictions (When Using the HF Connector)
・The anti-aliasing filter is bypassed. Therefore, remove unnecessary noise at high frequencies by
installing a proper low pass filter, band pass filter, tuning amplifier, etc. at the front. Otherwise, theoutput may fluctuate significantly.
・The HF connector retains the reference signal setting independently from other input connectors. If
the input connector is switched from another one, the frequency of the reference signal source,
external reference signal, and internal oscillator, etc. is switched to the HF connector setting.
・The external reference signal is limited to the TTL-level square wave. It does not work correctly withthe sine wave.
・The HF connector is always the AC coupling.
■ About Anti-aliasing Filter
The LI 5655 / LI 5660 converts an analog signal to a digital signal at 25 M samples/s and thenperforms digital signal processing. The anti-aliasing filter incorporated into the LI 5655 / LI 5660
removes frequency components above 3 MHz. Thus, noise at high frequencies is aliased close to thesignal frequency by sampling to prevent apparent noise from increasing.

4-20

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection7) Input Coupling *1
If A, A-B, or I is set, the input coupling [AC | DC] can be selected.
The specifics vary depending on the input connector. For details, refer to the figure below.
The C connector is always the DC coupling, but the DC component is automatically canceled.
The HF connector is always the AC coupling.
1M ｜100M
I

C

I-V

HF
1M｜50

I｜V

AC｜DC
Diff AMP

A

DC
CancelHF

C
Anti-Aliasing
Filter

B
AC｜DC
A-B｜A

DC
Cancel AC (AC coupling)
When a large DC component is included in the input signal, it is possible to measure the minute AC
signal by increasing the sensitivity by cutting the DC component. Increasing the sensitivity without
cutting off the DC component may cause internal circuitry to saturate.
Although the frequency characteristic of the AC coupling (DC cancel function) is corrected,
measurement accuracy decreases near the lower limit frequency. Also, transient response settling time isrequired when signal changes.
Please use AC coupling when the frequency is 1 Hz or more.
 DC (DC coupling)
For AC coupling, signal attenuation and phase error may increase at low frequencies.
For this reason, it is recommended to use DC coupling for frequencies below 1 Hz even for AC signalsthat do not contain DC components.
However, since the DC component is also regarded as noise, sufficient care is required for dynamic
reserve and sensitivity setting.

4-21

LI 5655 / LI 5660

4.5 Input Connector Setting and Connection

8) Select the GroundThe signal ground [FLOAT | GND] can be selected.
FLOAT: Floating from the enclosure (ground). Impedance to enclosure: 10 kΩ

GND: Connected to the enclosure. Impedance to enclosure: 11 Ω

If the signal grounds for the signal source and the LI 5655/ LI 5660 are grounded at separate locations, apotential difference between grounds (common-mode noise) may cause a noise current to flow into theground loop and a voltage drop in the signal ground line may be added as noise to the signal. In such acase, select FLOAT.

11 

ASignalsourceFLOAT / GND

DetailLI 5655 / LI 5660
10 k

r

L
FLOAT / GND

2
1

Common-mode
noise

2

±1 V max
If a large current flows between
both grounds, the clamp diode isdamaged.

If the signal source is not grounded, select GND and connect the signal ground to the enclosure of the
LI 5655 / LI 5660 to maintain the stability of the potential reference.
If the signal source is not grounded and the LI 5655 / LI 5660 is also in the FLOAT state, the impedance
to ground increases and the potential (to ground) of the signal ground fluctuates, for example, due to anelectrostatic coupling with the noise source. The fluctuation of the signal ground potential is an
isolation-mode rejection ratio whose characteristics are similar to those of the CMRR, which adversely
affects the signal measurement.
If the environmental noise is large
・If there is common-mode noise in the ground potential of the signal source and the signal reference
potential of the LI 5655 / LI 5660, use the differential connection (A-B).
・If the ground of the reference signal line (enclosure of the LI 5655 / LI 5660) is shared by the groundof the signal source to be measured, isolate the signal using a transformer.
・If noise comes in via the power supply or ground of an external device, the noise current can be
reduced by installing a noise cut transformer (NF Corporation's Noise Filter Transformer NT series,etc.) in the power line from the outlet. Furthermore, noise can be reduced in some cases byconnecting both grounds with low impedance to reduce the potential difference between grounds.

4-22

LI 5655 / LI 5660

4.6 Time Constant Filter Setting and Characteristics

4.6 Time Constant Filter Setting and Characteristics
The following shows how to set the time constant filter and attenuation slope.
The time constant filter characteristic is determined by the following three parameters.
 Time constant (TC) Attenuation slope (SLOPE) Synchronous filter (SYNC)
Set the filter to remove a ripple caused by the frequency and noise of the signal, or the phase sensitive
detector (PSD).

TC key(Operation screen selection key)

Left/right cursor keys

4.6.1 How to Set the Filter
In the measurement screen, the time constant can be set in the range of 1 μs to 50 ks using the left/rightcursor keys.
In the operation screen, first press the ＿TC＿ key to go to the following {Time Constant Filter Setting
Screen}.
1) Time Constant Setting{Time Constant Filter Setting Screen}
Press the [ TC ] soft key to set the time constantusing the MODIFY knob or up/down keys.
The setting range is 1 μs to 50 ks (1-2-5 sequence).

Setting range Current setting2) Attenuation Slope Setting{Time Constant Filter Setting Screen}
Press the [ SLOPE ] soft key to set the attenuation
slope using the MODIFY knob or up/down keys.
The setting range is 6, 12, 18, 24 dB/oct.

Setting range Current setting

4-23

LI 5655 / LI 5660

4.6 Time Constant Filter Setting and Characteristics

3) Select the Filter{Time Constant Filter Setting Screen}
Press the [ FILTER ] soft key to set the normal
filter (TC filter) and SYNC (synchronous filter)
using the MODIFY knob or up/down keys.

Setting range Current setting

4.6.2 Time Constant Filter Characteristics
1) Normal Filter
If the synchronous filter function is set to OFF, the characteristics are those of cascade-connected
first-order low pass filters (cutoff frequency fc). The attenuation slope per row is 6 dB/oct (20 dB/dec).
This characteristic is that if the frequency is doubled in the attenuation region, it is attenuated to 1 / 2 (ifthe frequency is increased by 10 times, it is attenuated to 1 / 10). Cascade-connect the filters in 1 to 4
rows to obtain an attenuation slope of 6 to 24 dB/oct (20 to 80 dB/dec).
First-order low pass filter

6dB/oct
PSD

12dB/oct
18dB/oct
Reference
signal24dB/oct1) Cascade connection of normal filtersa) Frequency Characteristics
6dB/oct

Gain / amplitude

Gain dB

利得 dB

0
-10
-20
-30
-40
-50
-60
-70
-80

24dB/oct

TC
Small
TC
Large

0
(Signal)

0.1

1

10

Noise
1F
2F
RippleF: Signal frequency

Normalized frequency

正規化周波数

Normalized frequency = |frequency difference from signal to reference| / cutoff frequency (fc)
fc = 1 / (2πT), T indicates the time constant.

4-24

LI 5655 / LI 5660

4.6 Time Constant Filter Setting and Characteristicsb) Equivalent Noise Bandwidth BN-3 dB bandwidth
Equivalent noise bandwidth

Sensitivity to white noise is represented by an equivalent noise
bandwidth. The bandwidth of an ideal filter where thesensitivity to noise (in other words, the RMS value of output
noise) is equal to that of the actual filter is called an equivalentnoise bandwidth of that filter.
Actual filter

Ideal filter

Equivalent noise bandwidth BN of the LI 5655 / LI 5660 is double the equivalent noise bandwidth of alow pass filter that is determined by time constant T and attenuation slope.
BN 6 

1
3
5
1, B N 12 
, B N 18 
, B N 24 
2T
4T
16T
32T

(corresponding to 6, 12, 18, and 24 dB/oct)

RMS value Vm of noise included in the output (measured value) can be obtained using the following
expression, where Vn indicates the noise density of the input and BN indicates the equivalent noise
bandwidth.

Vm  Vn  BNc) -3 dB Bandwidth B3dB

B3dB 

m

2  1  T 

T indicates the time constant, and m=1, 2, 3, 4 (corresponding to 6, 12, 18, 24 dB/oct)d) Step Response Time
Response y(t) to supplying a step signal to the low pass filter after phase sensitive detection isrepresented by the following expression.

m  Ttt n1
y0  0 , y (t )  1   n 1e
 n 1 T n  1!However, t  0 .

T indicates the time constant, and m=1, 2, 3, 4 (corresponding to 6, 12, 18, 24 dB/oct)
Step Response Time

90 %
99 %
99.9 %

6
2.3 T
4.6 T
6.9 T

SLOPE (dB/oct)
12
18
24
3.9 T
5.3 T
6.7 T
6.6 T
8.4 T
10.0 T9.2 T 11.2 T
13.1 T

This is the case of an analog filter. Digital processing
is used for the filter. Therefore the characteristic of
this device when the time constant is small varies

6dB/oct

1.0
Normalized
frequency
正規化振幅

Response

Step Response Waveform

0.8
24dB/oct

0.6
0.4
0.2
0.0
0

2

4

6

8

10

12

時間
(Tの倍数)
Time(multipleof T)slightly from the above.
4-25

LI 5655 / LI 5660

4.6 Time Constant Filter Setting and Characteristics

2) Synchronous Filter (SYNC)
If the synchronous filter function is set to ON, a moving average filter whose averaging section is equal
to a multiple of the signal cycle is added to the time constant filter.
If the time constant is decreased in the normal filter, the ripple caused by detection is not attenuated.
Since the time constant must be increased to a certain extent even if noise is small, the output response isslow in particular at low frequencies.
An integer-cycle moving average filter significantly attenuates the ripple caused by detection.
Therefore, a high-speed response can be obtained by decreasing the time constant (almost corresponding
to the averaging section) if noise is small.
If the time constant is smaller than the signal cycle, the step response is set to approximately 1 signal
cycle.
Actually, the normal filter is placed at the rear stage of the moving average filter.
Therefore, if the time constant is increased, the response is closer to that of the normal filter (the ripple isattenuated more significantly).
Frequency characteristics of the moving average filter

Configuration of the synchronous filter

Gain / amplitude(Example: Averaging section = 1 cycle)
PSD

Reference
signal

1F
2F
RippleF: Signal frequency

Moving average filter

Normal filter
cascadeconnection

If you need a high-speed response, set 6 dB/oct for the attenuation slope. However, the output waveform
looks slightly like a series of steps.
The practical upper limit frequency of the synchronous filter is about 1 MHz. If the signal frequency is
increased, the averaging section may deviate slightly from the integer cycle and sufficient reduction of
the ripple may not be possible.

4-26

LI 5655 / LI 5660

4.6 Time Constant Filter Setting and Characteristics

4.6.3 Auto Setting of Time ConstantPress [TIME CONST] in the {Auto Setting Screen} ( ＿AUTO＿ key ) to automatically set the time constantand attenuation slope as shown below according to the frequency.
 Attenuation slope (SLOPE) = 24 dB / oct Synchronous filter (SYNC) = Valid if frequency ≦ 100Hz, invalid if frequency > 100Hz Time constant (TC) = 10 ÷ ( 2 × π × signal frequency)* However, the calculated value is rounded up to the nearest setting value.
The time constant range is 20 μs ≦ TC ≦ 20 s.
* Firmware version 1.60 or later
If the measurement fails using auto setting, use manual adjustment.
If the measured value fluctuates due to noise or insufficient ripple removal, increase the time constant.
If you need a faster response, decrease the time constant.
In general, noise reduction and response time can be balanced better if the attenuation slope is increased
and the time constant is decreased. However, if the LI 5655 / LI 5660 is used in an automatic control loop,
the control system may be unstable due to the characteristics of a high-order filter. In such a case, set 6 dB /oct for the attenuation slope. If the ripple caused by detection may not be attenuated sufficiently, consider
using the synchronous filter.
If a DC offset is included in the PSD input, a ripple of the same frequency as the signal frequency is
included in the phase-detected output. A large time constant is required to remove it.
As a result, the response is slower.
The occurrence of this ripple can be suppressed and an unnecessarily large time constant does not need to
be set by adjusting the PSD input offset to zero.
For details on the adjustment of the PSD input offset,  "5.7 PSD Input Offset Adjustment"

4-27

LI 5655 / LI 5660

4.7 Sensitivity and Dynamic Reserve Setting

4.7 Sensitivity and Dynamic Reserve Setting
The following shows how to set the sensitivity (signal full scale) and dynamic reserve (noise margin).
Up/down keys
SENS key(Operation Screen Selection Keys)

4.7.1 How to Set the Sensitivity
In the measurement screen, the sensitivity range can be set for each of the following input connectors using
the up/down keys.
Measurement
Sensitivity range *2
setting
Voltage
10 nV to1V
sensitivity
A
A-B
Voltage noise
20 nV to1 V *3density
Voltage
1 mV to10 V
sensitivity
C *1
Voltage noise
1 mV to10 V *3
density
Current
100 fA to
1 μA
sensitivity
1 M〔V/A〕
Current noise
1 pA to
1 μA *3
densityI
Current
10 fA to10 nA
sensitivity
100M〔V/A〕
Current noise
100 fA to
10 nA *3
density
Voltage
1 mV to1V
sensitivity
HF *1
Voltage noise
1 mV to1 V *3density*1: Only the LI 5660 is equipped with the C and HF connectors.
Input connector *4*2: The magnitude of the signal that is displayed is the root mean square (RMS).
The sensitivity setting value is the full scale and the sequence is 1-2-5.
For details on the display range,

 "9.5 Measured Value Output and Display Section, e) Numeric display"*3: When the noise density (NOISE) is displayed, add / Hz to the unit that is displayed when
you read it.
*4: The sensitivity settings are retained for each connector. The settings for the A and A-B
connectors are commonly retained, and the settings for the 1 M and 100 M conversion of the I
connectors are retained individually.

4-28

LI 5655 / LI 5660

4.7 Sensitivity and Dynamic Reserve Setting

In the operation screen, first press the

SENS

key to go to the following {Sensitivity Setting Screen}.

1) Sensitivity Setting{Sensitivity Setting Screen}
Press the [ SENS ] soft key to set the sensitivity using
the MODIFY knob or up/down keys.

Setting range

Current setting2) Dynamic Reserve Setting{Sensitivity Setting Screen}
Press the [ DR ] soft key to set the dynamic reserveusing the MODIFY knob or up/down keys.
The setting parameters are LOW, MED, and HIGH.
The margin for noise is larger on the HIGH side.
Set a minimum value for the dynamic reserve. The
input referred noise is larger or the drift of theCurrent setting

Setting range

measured value is larger on the HIGH side.

■ Dynamic Reserve at a Specific Frequency
The dynamic reserve value depends on the saturation signal

Sensitivity(Signal fullscale)and the characteristics of removing noise using the time
constant filter. In other words, it depends on the frequency.
Dynamic
reserve

Time constantfilterlevel inside the device at a specific sensitivity (signal full scale)(Signal frequency)

Saturation
signallevel

0Frequency
deviation

Dynamic reserve value at a frequency where noise is attenuatedsufficiently by the time constant filter
For details,  "9.2 Phase Sensitive Detector Section,c)Dynamic Reserve (DR)■ Dynamic Reserve for Random Noise
Random noise (wideband noise) is acceptable until its peak value reaches the saturation signal level
inside the device. The RMS values of sine wave and noise are equal to each other, but the peakvalue of the noise is several times or more larger than that of the sine wave. Set the dynamic reserve
considering the peak value.

4-29

LI 5655 / LI 5660

4.7 Sensitivity and Dynamic Reserve Setting3) Auto Sensitivity Adjustment Setting
Icon indicating auto sensitivity adjustment is running{Sensitivity Setting Screen}

Press the [ AUTO ]soft key to set HOLD or AUTO for
the auto sensitivity adjustment using the MODIFY
knob or up/down keys.
AUTO

continuously

automaticallyadjusts

thesensitivity and dynamic reserve according to themagnitude of the signal and noise.
HOLD retains the sensitivity and dynamic reserve
Settable parameters

Current setting

settings. It sets the manual setting to ON.

■ Restrictions (Operations in AUTO Mode)
If any of the following operations is performed in AUTO, the auto sensitivity setting isforced to be changed to HOLD.
 When the offset value is changed using the ＿DATA＿ key and [ OFFSET> ] soft key.
 When the arithmetic processing function is changed using the ＿ DATA ＿ key and[ MATH> ] soft key.
 When a change is made to the time constant filter settings using the ＿TC＿ key.
 When a change is made to the input connector settings using the ＿SIG＿ key.
 When the phase shift amount is changed using the ＿PHASE＿ key.
 When a change is made to the reference signal settings using the ＿REF＿ key.
 When the sensitivity or dynamic reserve is changed from the measurement screen or
operation screen.

4.7.2 Sensitivity and Dynamic Reserve Auto Setting
Press the [SENS] soft key in the {Auto Setting Screen} ( ＿AUTO＿ key) to automatically set the sensitivity
and dynamic reserve just once according to the magnitude of the signal and noise.
In the following cases, the auto setting is forced to be terminated after switching the sensitivity several
times, so the sensitivity may not be set properly.
 When the signal fluctuates significantly
 When the noise is large When the signal is small
If the signal fluctuates significantly, perform the auto sensitivity setting and then perform the manual
operation in a slightly larger range. If fluctuations due to noise are large, set a larger value for the time
constant and attenuation slope and then perform the auto setting again. If the signal is small, set thesensitivity and dynamic reserve by manual operation.

4-30

LI 5655 / LI 5660

4.7 Sensitivity and Dynamic Reserve Setting

4.7.3 Signal Over-level Display and Monitor Output
If an excessive signal level is detected anywhere on the signal path from the LI 5655 / LI 5660 input tooutput and measurement is impossible, an icon is displayed in the screen.
Over-levelstatusIN/OUTINPUTOUTPUT

AUX

A
B

RemedyVoltage exceeding the maximum input
voltage was detected in the A or B
connector.
Both the A and B connectors are internallyseparated temporarily for protection.
Both events described in INPUT and
OUTPUT below occurred.
Over-leveloccurredintheAC
amplification part from the signal input
connector to PSD (primary PSD) input.
The PSD input signal can be checked with
the MONITOR OUT connector.

Lower the signal level applied to the A
or B connector.
Use the C connector. (For the LI 5660
only)Over-level occurred in the signal
processing part of the PSD output (timeconstant filter and DC amplification part).
The output voltage range was exceeded asa result of an OFFSET, EXPAND,NORMALIZE,RATIO,orotherarithmetic processing.
Measurement parameters that are not
output and displayed are also included in
the scope.
Excessive input into the AUX IN 1 or
AUX IN 2 connector.
PROTECT

INPUT

Diff

OVER LEVEL DETECTORPROTECT

Description

C

HF

I

I-V

(See below)
Increase the sensitivity (signal fullscale).
Increase the dynamic reserve.
If a DC component is included in the
input signal, use the AC coupling.
Set the line filter to ON to attenuate thenoise coming from the power supply.
Increase the time constant andattenuation slope to attenuate the noise.
Increase the sensitivity (signal fullscale).
Cancel the arithmetic processing andcheck the original signals (X, Y, R, AUX
IN 1). Then configure the setting again
so the output does not exceed the
maximum level.
Lower the signal level applied to the
AUX IN 1 or AUX IN 2 connector.

OUTPUT

PSD

TC Filter(LPF) DC Amp

EXPANDDATA OUTNORMALIZE

REF

OFFSETMONITOR OUT

RATIO (a / b)

AUX IN 1

AC Amp*1：: Only the LI 5660 isequipped with C and HF.

AUX IN 2
AUX

Over-level Detection Block Diagram

4-31

LI 5655 / LI 5660

4.7 Sensitivity and Dynamic Reserve Setting

Over-level status

MONITOR OUT

When more than one event occurs at the same time, their display priority status is according to the abovetable.
Do not connect an unnecessary signal to the LI 5655 / LI 5660 as the measurement may be affected. A
signal exceeding the maximum input level of the input connector cannot be measured correctly. Check thatthe signal level is within the specification range using an oscilloscope, etc.
■ Monitor Output
The input signal of the PSD (primary PSD) can be checked with the MONITOR OUT connector.
If the measurement is not successful, check the monitor output using an oscilloscope, etc.
Gain from the input (A, A-B, C *1, I, HF *1) to the monitor output is equivalent to the AC gain.
For the AC gain, refer to the sensitivity setting and dynamic reserve setting, and the table in "9.2
Phase Detection Part c) Dynamic Reserve (DR)."For input I, multiply it by a factor of the current-to-voltage conversion gain (106 V/A for 1 M and 108
V/A for 100 M).
For input C, multiply the AC gain by a factor of 1 / 10 for the attenuator.
Note that the phase is largely shifted by the anti-aliasing filter, so the monitor output phasesignificantly differs from the measured phase. Therefore, it is not suitable for checking the signal
phase.
*1: Only the LI 5660 is equipped with the C and HF connectors.

4-32

LI 5655 / LI 5660

4.8 Phase Adjustment

4.8 Phase Adjustment
In general, the phase reference (0°) of a lock-in amplifier can be shifted arbitrarily.
The basic usage is to adjust the phase of the reference signal to be applied to the PSD so Y output is equal
to 0 (θ = 0), and then measure the magnitude of the signal in the X output and changes in the phase in the Y

2 times larger in the R output than those in the X output.

output. Fluctuations due to random noise are

If the magnitude of the signal is constant, the Y output close to zero is almost in proportion to θ, and aminute phase change can be detected with high sensitivity by increasing the EXPAND scale factor (to x10
or x100).
PSD
Reference
signalSignal

Y
R

R

θ

θ
X

REF IN=PSD reference signal

SignalPSD
Reference
signalY' = 0

X' = Rθ' = 0REF IN

Phase shift amount = 0

Phase shift amount = -θ1) Phase SettingFirst press the ＿PHASE＿ key to go to the following {Phase Adjustment Screen}.
{Phase Adjustment Screen}
When you enter the operation screen, you canmove through the digits using the left/rightcursor keys and then set the numerical value
using the MODIFY knob or up/down keys.

Setting range

Current set value

Press the [ ZERO ] soft key to set the phase shift amount for the reference signal to 0° .
Press the [ +90°R ] soft key to increase the phase shift amount for the reference signal by 90° .
Press the [ -90°R ] soft key to decrease the phase shift amount for the reference signal by 90° .
In the LI 5655 / LI 5660, when increasing (decreasing) the phase shift amount, the phase measurement
value increases (decreases).
2) Auto Phase Adjustment
Press the [PHASE] soft key in the {Auto Setting Screen} ( ＿AUTO key) to set the phase shift amountfor the reference signal just once so the Y output and the θ output are equal to zero.
If the auto phase adjustment is executed while the signal is not synchronized with the reference signal,
an error occurs.
4-33

LI 5655 / LI 5660

4.8 Phase Adjustment(Blank)4-34

LI 5655 / LI 5660

5． Advanced Operations

5.1 Measured Value Offset and Expansion ................................. 5-3
5.2 Line Frequency Noise Removal ............................................ 5-5
5.3 Harmonic Measurement (Harmonic, Subharmonic,
Fractional Harmonic) ............................................................. 5-6
5.4 External 10 MHz Synchronization ......................................... 5-7
5.5 Arithmetic Processing (Normalize and Ratio) ....................... 5-8
5.5.1 Normalize (%, dB, etc.) ............................................................ 5-8
5.5.2 Ratio Measurement ................................................................ 5-10

5.6 Noise Density Measurement ...............................................5-12
5.6.1 Noise Density Measurement Operation .................................. 5-12
5.6.2 Noise Density Measurement Principle .................................... 5-14

5.7 PSD Input Offset Adjustment ..............................................5-15
5.8 DC Voltage Measurement (AUX IN) ...................................5-17
5.9 DC Voltage Output (AUX OUT)...........................................5-19
5.10 Supplying Power to the Preamplifier..................................5-20
5.11 Setting Memory ..................................................................5-21
5.12 Other Functions..................................................................5-23
5.12.1 Disable the Panel Operation (KEY LOCK) ............................. 5-23
5.12.2 Lamp Off (LAMP OFF) ........................................................... 5-23

5-1

LI 5655 / LI 5660

4.8 Phase Adjustment

This chapter describes the more advanced usage that is not covered in "4. Basic Operations."
For details on dual frequency measurement,  "6．Dual Frequency Measurement"

5-2

LI 5655 / LI 5660

5.1 Measured Value Offset and Expansion

5.1 Measured Value Offset and Expansion
An offset (OFFSET) can be applied to the measured value (X and Y).
A fixed crosstalk component included in the input signal can be canceled using the offset function.
Furthermore, offset adjustment can be performed to bring the measured value close to zero and expand

Y OFFSET(EXPAND) a small change and observe it.
SignalYRθ

Expand

Y'
R'

R

θ'

θ
X

{Fine Measurement Screen}

X'

X OFFSETPSD reference signal

When the offset function is set to ON, the "OFS" icon isdisplayed in the measurement data field.
The offset adjustment value is displayed in MATHSETTING on the lower right corner of the finemeasurement screen.
When the EXPAND function is set to ON, an icon
showing a setting expansion value such as "x10" isdisplayed in the measurement data field.

First press the ＿DATA＿ key to go to the following {Output Signal Setting Screen}.
{Output Signal Setting Screen}＿DATA＿ key(Operation screen selection
key)

5-3

LI 5655 / LI 5660

5.1 Measured Value Offset and Expansion

1) Offset{Offset Adjustment Screen}

Next press the [ OFFSET> ] soft key to go to the{Offset Setting Screen}
Press the [ OFFSET ] soft key to move through the digits
using the left/right cursor keys and then set thenumerical value using the MODIFY knob or up/downkeys.

Setting range
Current set
value

ON / OFF for thefunction
Offset target

Press the [ X｜Y ] soft key to select the target (X or Y) to
set the offset value.
Press the [ ON｜OFF ] soft key to switch between ON
and OFF for the offset adjustment. The offset value canbe set individually for X and Y.

Press the [ AUTO once ] soft key to execute the auto offset adjustment only once to set the X and Y
outputs to zero. When the auto setting is completed, the offset adjustment is set to ON.
2) Expansion{Expansion Setting Screen}

Next press the [ MATH> ] soft key to go to the {MathSelection

Screen}Select"EXPAND"

using

the

MODIFY knob or up/down keys
to display the [ EXPAND> ] soft key.
Press the [ EXPAND> ] soft key to go to the {Expansion
Setting Screen}.
Press the [ RX ] or [ Y ] soft key to set the expansion
Setting range

Current set value

value {x1｜x10｜x100} using the MODIFY knob or
up/down keys.
The expansion value for measurement data R and X isshared and the expansion value for Y is set individually.

The apparent sensitivity (signal full scale) can be expanded 0.1 times or 0.01 times using EXPAND.
■ Restrictions
Only detector outputs X, Y, and R can be expanded. If the X and Y offset adjustment is performed, theadjusted value is expanded.
Other parameters (phase, noise density, and AUX IN) cannot be expanded.
EXPAND is not executed while the normalize arithmetic processing or the ratio arithmetic processing
is executed.

5-4

LI 5655 / LI 5660

5.2 Line Frequency Noise Removal

5.2 Line Frequency Noise Removal
A line filter (notch filter) to remove noise from the power supply included in the input signal is available.
Line frequency noise removal has the following benefits.
 Dynamic reserve can be set to a smaller value to improve the measurement accuracy.
 Time constant and attenuation slope can be set to a smaller value to increase theresponse speed.
However, the transient response of the line filter may impact the measurement.
To set the power line filter, first press the SIG key to go to the {Input Signal Selection Screen}.
Next press the [ LINE NOTCH> ] soft key to go to the{Line Filter Setting Screen}{Line Filter Setting Screen}.
The frequency of the line filter can be selected from
{THRU｜50 Hz｜100 Hz｜50 Hz&100 Hz} using the
MODIFY knob or up/down keys.
Press the [ LINE FREQ> ] soft key to go to the {LineFrequency Selection Screen}.
The line frequency (fundamental wave) can be selected
Setting range

from {50 Hz｜60 Hz} using the MODIFY knob or

Current setting

up/down keys.
Frequency Hz （ x 2）
80

90

100

110

120

130

140

0

Gain dB

-5
-10

fc =
50, 100 Hz

fc =60, 120 Hz-15
fc: Center
frequency
-20
-25
40

45

50

55

60

65

70

Frequency Hz （x 1）

Figure 5-1 Line Filter Characteristics
50 Hz (60 Hz) and 100 Hz (120 Hz) can be cascade connected. The approximate characteristic of themeasured value is corrected up to a gain of about -6 dB to prevent the attenuation. If the correction limit isexceeded, the correction amount is fixed to the limit value.
■ Restrictions (Only for the LI 5660)
If the C or HF connector is selected, the line frequency filter cannot be set.

5-5

LI 5655 / LI 5660

5.3 Harmonic Measurement (Harmonic, Subharmonic, Fractional Harmonic)

5.3 Harmonic Measurement (Harmonic, Subharmonic, Fractional
Harmonic)
Fundamental wave (F), harmonic (n x F), subharmonic (F / m), and fractional harmonic (n x F / m) can bemeasured, where F is the frequency of the reference signal.
{Harmonic Setting Screen}

To set the harmonic measurement, first press the＿REF＿ key to go to the {Reference Signal Setting
Screen}.
Next press the [ HMNC> ] soft key to go to the{Harmonic Setting Screen}.
Press the [ HARMONICS ] soft key to select ON or OFF
for the harmonic using the MODIFY knob or up/down

Setting range

Current setting

keys.

Press the [ n ] soft key for the order of the harmonic and press the [ m ] soft key for the order of thesubharmonic to move through the digits using the left/right cursor keys and then set the numerical value
using the MODIFY knob or up/down keys.
The setting range is 1 to 63 for both n and m.
If the harmonic setting is set to ON, small letter "n" is added to the measurement parameter regardless ofthe harmonic order.
■ Restrictions
 If the measurement signal (SIGNAL) is selected for the reference signal source, theharmonic order is always 1 regardless of the harmonic setting of n or m.
 The frequency range of the harmonic that can be measured is limited to thesynchronous frequency range of each input.
If the synchronous frequency range is exceeded, "OVER-FREQ" or "UNDER-FREQ" isdisplayed in the frequency display field.

5-6

LI 5655 / LI 5660

5.4 External 10 MHz Synchronization

5.4 External 10 MHz Synchronization
The frequency reference source of the LI 5655 / LI 5660 can be synchronized with other devices (such as asignal generator).
If an external 10 MHz frequency reference source is connected to the 10MHz IN connector, the frequency
synthesizer comprising the internal oscillator of the LI 5655 / LI 5660 is synchronized with the external
10 MHz.
Synchronizing operation allows synchronization to any frequency (can be configured) without having touse an external reference signal (REF IN). It makes it possible to perform measurements synchronized not
only with the numerical value setting (INT OSC) but also with an external reference signal (REF IN) or
measured signal (SIGNAL).
However, the phase does not match, so phase adjustment is required every time the frequency is changed.
In general, once the signal (oscillation) stops, the phase is shifted, so phase adjustment is required again.
External 10 MHz specifications
For details,  "9.3 Reference Signal System c) Internal Oscillator
External Reference Frequency"
LI 5655 / LI 5660
EXT OSC
Frequency

SIGNAL
INPUT

SystemUnder
Test

10MHz IN

DATA
OUT

PSD

OSC
OUT
10MHz IN
10MHz
Frequency
sourceINT OSC10MHz
REF OUT

Frequency(Numerical value)

Figure 5-2 10 MHz Synchronous System Example
To set the external 10 MHz, first press the ＿REF＿ key to go to the {Reference Signal Setting Screen}.
{External 10 MHz Setting Screen}

Next press the [ OSC SET> ] soft key to go to the{Internal Oscillation Setting Screen}.
Press the [ 10MHz In> ] soft key to go to the {External
10 MHz Setting Screen}.
ON or OFF can be selected using the MODIFY knob or
up/down keys.
If ON is set, theicon is displayed.

If a 10 MHz signal is input from 10MHz IN connector
Current settingin this state, the color of the icon changes

andsynchronization is established.

5-7

LI 5655 / LI 5660

5.5 Arithmetic Processing (Normalize and Ratio)

5.5 Arithmetic Processing (Normalize and Ratio)
To perform an arithmetic processing (normalize or ratio), first press the ＿DATA＿ key to go to the {Output
Signal Setting Screen}.
{Math Selection Screen}
Next press the [ MATH> ] soft key to go to the{Math Selection Screen}.
Selectarithmetic

processing

EXPAND,NORMALIZE, or RATIO using the MODIFY
knob or up/down keys to display the soft key foreach arithmetic processing.
Current setting Press the selected arithmetic processing soft key to set
each arithmetic processing function.

Settable parameters5.5.1 Normalize (%, dB, etc.)
The ratio of measured values X and R to the standard value and sensitivity (signal full scale) can be output
and displayed in % or dB.
1) Select the Operation Expression{Normalize Setting Screen}
Press the [ NORMALIZE ] soft key to go to the{Normalize Setting Screen}.
The normalize arithmetic expression can beselected using the MODIFY knob or up/downkeys.
・％： (measured value ÷ standard value) x 100[%]
Settable parameters

Current setting

Display range is ±240%
・dB： 20 × log10 (|measured value ÷ standard
value|) [dB]
Display range is ±120 dB
・%FS：(measured value ÷ sensitivity setting) x
100 [%FS]
Display range is ±120% of FS

5-8

LI 5655 / LI 5660

5.5 Arithmetic Processing (Normalize and Ratio)2) Standard Value Setting{Standard Value Setting Screen}
Press the [ STD> ] soft key to go to the {Standard
Value Setting Screen}.
Move through the digits using the left/rightcursor keys and then set the numerical value
using the MODIFY knob or up/down keys.
The setting range is as follows.
・Voltage: 1 nV to 10 V (6-digit resolution)
Settable parameters

Current set value・Current: 1 fA to 1 μA (6-digit resolution)
The setting range is switched for the voltage
measurement and current measurement.

3) User Unit Setting{Normalize Setting Screen}

Press the [ USER UNIT ] soft key to move through thedigits using the left/right cursor keys and set the user
unit string (1 to 3 characters) using the MODIFY knob
or up/down keys.
The user unit string is displayed in place of the normal
unit (%, etc). Alphanumeric characters (A-Z, a-z, 0-9)

Settable characters

Current setting

and some symbols (#, @, -), and blank can be used. If"_" is set, a blank " " is displayed.

Reset or press the ＿CLR＿ key to display "_ _ _" in the setting screen and restore the normal unit.
■ Restrictions
The normalize arithmetic processing is performed for detector outputs X and R. The normalize
arithmetic processing is not performed for other parameters (Y, θ, noise density, and AUX IN).
The normalize arithmetic processing cannot be executed while the ratio arithmetic processing or
EXPAND arithmetic processing is executed.

5-9

LI 5655 / LI 5660

5.5 Arithmetic Processing (Normalize and Ratio)

5.5.2 Ratio Measurement
The LI 5655 / LI 5660 outputs and displays detector outputs X, Y, and R as a ratio to the signal (AUX IN 1)
that is used as a reference to the magnitude.
If a sample inserted into the signal path is measured in a situation where the characteristics of the signal
source and sensor fluctuate, measure the characteristics of the path that is used as a reference separately andobtain the ratio of them to correct the fluctuations in the common part to ensure that the measurement iscorrect. A dual beam method shown below measures the characteristics of the path that is used as areference at a different frequency using two lock-in amplifiers to obtain a result where the characteristics ofthe light source and sensor are corrected.
SamplecellLightsourcef1 & f2

f1

Lock-in Amplifire 1

SensorIa

A

REF INf2

OUT

f1
AUX IN 1

Reference
cellLight chopperor
Optical modulator

RATIO
a/b

b
f1
f2

f2

Lock-in Amplifire 2
Figure 5-3 Ratio Measurement Application Example (Dual Beam Method)
The LI 5655 / LI 5660 can perform this ratio measurement by itself.
For details,  "6.9

Ratio Measurement (Dual Frequency Measurement)"

1) Ratio Setting{Ratio Setting Screen}

Press the [ K ] soft key in the {Ratio Setting
Screen} to move through the digits using theleft/right cursor keys and then set the K constantusing the MODIFY knob or up/down keys.

Setting range

Current set value

Ratio display value = K x (A ÷ B)
K: Ratio scale factor setting value(Range 0.1 to 10, 6-digit resolution)
A: Measurement display values (X, Y, R) ÷sensitivity setting value
Value after the X and Y offset adjustment
is performed.
B: AUX IN 1〔V〕÷10 V
Ratio display range is ±2.4
If the ratio calculation result is +2.0, the analog
output is +10 V.

5-10

LI 5655 / LI 5660

5.5 Arithmetic Processing (Normalize and Ratio)

2) Reference Value (AUX IN 1)
A reference signal is input into the AUX IN 1 connector on the rear
panel.
The reference signal that is used as the denominator of the ratio
calculation must be 1 V or more (the maximum allowable input voltage
is ±12 V) to reduce an error.
Although the frequency bandwidth of AUX IN is 5 kHz, the maximum
update rate of B is about 10k samples/s, and a rapidly changing signal
cannot be followed. So input a slowly changing signal of about 100 Hz or less.
■ Restrictions
The ratio arithmetic processing is performed for detector outputs X, Y, and R. The ratio arithmetic
processing is not performed for other parameters (θ, noise density, and AUX IN).
The ratio arithmetic processing cannot be executed while the normalize arithmetic processing or
EXPAND arithmetic processing is executed.

5-11

LI 5655 / LI 5660

5.6 Noise Density Measurement

5.6 Noise Density Measurement
5.6.1 Noise Density Measurement Operation
The following shows how to measure the noise density.
First press the ＿DATA＿ key to go to the {Output Signal Setting Screen}.
{Output Signal Setting Screen}
DATA key(Operation screen
selection key)1) Display the Noise Density{Basic Measurement Parameter Setting Screen}
To display the noise density, press the [ BASIC> ]soft key and then the [ NOISE-AUX1 ] soft key.
NOISE and AUX IN 1 are set in DATA1 andDATA2, respectively. (Other settings are notchanged.){Custom Measurement Parameter Setting Screen}
Press the [ CUSTOM> ] soft key and then the[ DATA1 ] soft key to select "NOIS" using the
MODIFY knob or up/down keys. NOISE is set in
DATA1. (Other settings are not changed.)

2) Set the Time Constant
For the time constant (TC), set 1 ms or more, or a value of 10 times or more the signal cycle to bemeasured, and for the attenuation slope (SLOPE), set about 24 dB / oct, if there is no particular problem.
If the time constant and attenuation slope are too small, noise at distant frequencies or a ripple caused byphase sensitive detection may also be measured together. Therefore, the noise density may appear to belarger.
If the noise density decreases by increasing the time constant and attenuation slope, the time constantand attenuation slope are too small. If the time constant is increased, it takes longer to perform themeasurement, so perform the manual adjustment as needed.

5-12

LI 5655 / LI 5660

5.6 Noise Density Measurement

3) Set the Smoothing Factor{Output Signal Setting Screen}

Setting range

Current setting

If you return to the {Output Signal Setting
Screen}, the [ NOISE ] soft key is displayed.
Press the [ NOISE ] soft key to set the smoothing
factor (1, 4, 16, 64) using the MODIFY knob or
up/down keys.
Display example) N16: Smoothing factor = 16
If the smoothing factor is multiplied by 4, thefluctuations of the measured value decrease toabout a half.

However, it takes a long time until the measured value is stabilized. By observing the variation of thefollowing equation over time, read the median value, and use it as the measurement result.
200 x smoothing factor x time constant〔in seconds〕
4) Set the Sensitivity
The measurement full scale of the noise density is set in SENS (sensitivity).
Measurement
Input connector
Sensitivity range*2
setting
Voltage noise
20 nV to1 V *3A，A-B
density
Voltage noise
1 mV to10 V *3
C *1
density
Current noise
1 pA to
1 μA *3
1M〔V/A〕
densityI
Current noise
100 fA to 10 nA *3
100M〔V/A〕
density
Voltage noise
1 mV to1 V *3
HF *1
density*1: Only the LI 5660 is equipped with the C and HF connectors.
*2: The sensitivity setting value of the noise density is the full scale and the sequence is 1-2-5.
For details on the display range,
 "9.5 Measured Value Output and Display Section e) Numeric display"*3: The units of the noise density (NOISE) are Vrms / Hz (voltage) and Arms / Hz (current).
Only V or A is displayed in the measurement screen.
Add "／ Hz " to the unit that is displayed when you read it.
If there is the same frequency component as the measurement frequency, the noise density cannot bemeasured correctly. Furthermore, if a noise other than the measurement frequency is large, the dynamic
reserve must be increased.
If "OVER" is displayed even if the measured value is sufficiently smaller than the full scale, increase thedynamic reserve or increase the sensitivity (signal full scale). However, if the dynamic reserve isincreased, the input referred noise of this device increases.
There is a relationship for white noise as shown below.
Noise density measured value= Input referred noise density of this device2  Input signal noise density2

5-13

LI 5655 / LI 5660

5.6 Noise Density Measurement
Noise density 4.5 nV/ Hz (supplementary value) in the specifications is that when the dynamic
reserve is LOW, 1 kHz and the sensitivity is 1 mV or less.
A noise smaller than that of the LI 5655 / LI 5660 cannot be measured. Use an external low-noise
preamplifier (NF Corporation's SA series, etc.) to amplify the noise and measure it.
■ Supplementary Explanation
There are some cautions for the noise density measurement.
 The noise density measurement results vary depending on the selection of thesensitivity, dynamic reserve, time constant, and attenuation slope.
 If the time constant and attenuation slope are too small, other signals may bemeasured together.
When the sensitivity and time constant settings are determined, check the noise densityof the LI 5655 / LI 5660 in a non-input-signal state. For the voltage measurement,
short-circuit the input, and for the current measurement, open the input circuit (cover
the input connector with a shield cap to protect against ambient noise) and measure thenoise.
Then input the signal (noise) to be measured and check that the measured noise issufficiently larger than the previously mearured LI 5655 / LI 5660 's own noise.

5.6.2 Noise Density Measurement Principle
If the RMS value (Vm) of a signal is measured by passing it through a filter with an equivalent noise
bandwidth of BN, the noise density (Vn) can be obtained by the following formula.

Vn  VmBN

A lock-in amplifier works as a band pass filter that uses the frequency (fr) of the reference signal as thecenter frequency. A normal measurement measures only the center frequency, but a noise measurement
measures the RMS values of all components of the band.
Actually a high pass filter is installed after a band limiting filter to remove the reference signal frequency
components (DC components after phase sensitive detection) and obtain the RMS values. This prevents theinfluence of leak-in of the reference signal and the periodic fluctuations of the measured noise values.
The equivalent noise bandwidth (Bbp) for the noise measurement is a little narrower than that for measuring
the magnitude of a signal. Therefore, the noise density is calculated using the equivalent noise bandwidth
for the noise density.
BN

BN/2
PSD

f

Bbp/2 < BN/2
HPF

0(DC)

r
For a normal measurement,
obtain the DC components.

0(DC)

fr

For a noise density measurement, calculate
from the total RMS value in band andequivalent noise bandwidth.

Figure 5-4 Noise Measurement and Bandwidth

5-14

LI 5655 / LI 5660

5.7 PSD Input Offset Adjustment

5.7 PSD Input Offset Adjustment
The LI 5655 / LI 5660 has a function to cancel the DC offset of the PSD input.
If a DC component is included in the PSD input, a 1F ripple that is equal to the measurement frequency (F)occurs in the detection output. A large time constant is required to remove the 1F ripple. This slows theoutput response. If a high-speed response is needed at high frequencies, it is recommended to perform the
PSD input offset adjustment. It is useful to use a synchronous filter at low frequency measurement.
DC

PSD

TC Filter

SIG

REF
0

1F

2F

Frequency

If a large DC component is included in the input signal, set AC for the input coupling.
The PSD offset adjustment function of the LI 5655 / LI 5660 cancels a small DC offset that occurs in the
LI 5655 / LI 5660.
1) PSD Input Offset Adjustment Operation{PSD Adjustment Screen}First press the ＿TC＿ key to go to the {Time ConstantSetting Screen}.
Press the [ PSD ADJ> ] soft key to go to the {PSD
Adjustment Screen}.
To perform the auto adjustment of the PSD input offset
only once, press the [ AUTO once> ] soft key.

{PSD Adjustment Confirmation Screen}

The

{PSD

Adjustment

Confirmation

Screen}isdisplayed. Keep the input connector in a non-signal
state.
Press the [ Exec ] soft key to execute the auto
adjustment.
Press the [ Cancel ] soft key to go back to the previous
screen.

 How to Set the Input Signal to Zero
Voltage measurement: Short-circuit the input connector using a short plug or 50 Ω terminator.

Current measurement: Cover the input connector with a shield cap or leave it open.
If the center contact is not shielded and is open, keep metals and dielectricmaterials where the potential fluctuates away from it to prevent noise
coupling.

5-15

LI 5655 / LI 5660

5.7 PSD Input Offset Adjustment

 Preparations
The following preparations are needed to execute AUTO once.
 Determine the actual operating conditions.
If measurement conditions such as the signal input connector and sensitivity arechanged, adjustment is required again.
 Set the input signal to zero.
 Perform the warm-up appropriately.
It can reduce drift after the adjustment.
Furthermore, keep the power voltage and ambient temperature as constant as possible.
If the continuous auto adjustment operation is used, those preparations are not needed.
2) PSD Input Offset Continuous Auto Adjustment Operation{PSD Adjustment Screen}
Press the [ AUTO ] soft key from the {PSD Adjustment
Screen} to select AUTO or HOLD in the continuous auto
setting using the MODIFY knob or up/down keys.
・AUTO: Performs the continuous auto adjustment
operation.
・HOLD: Holds the last adjustment value.

Settable parameters

Current setting

The PSD icon is displayed during the execution of thecontinuous auto adjustment operation.

Press the [ DEFAULT ] soft key to reset the adjustment value to the factory default value and hold it.
Press the [ SETLG TIME ] soft key to set 200 ms, 750 ms,
or 3000 ms for the settling time using the MODIFY knob
or up/down keys.
The input offset (DC component) can be adjusted up to
25% of full-scale sensitivity.
The settling time refers to the time it takes for the input
offset to settle to approximately 2% if it is 100%.

100%

2%

0%
SETLG TIME

Response characteristics (for thecontinuous auto adjustment operation)

For the continuous auto adjustment operation, the signal gain decreases at low frequencies so ameasurement error increases.
Use approximately 320 Hz or more if 200 ms is set, 85 Hz or more if 750 ms is set, and 21 Hz or more if
3000 ms is set.
If the adjustment range is exceeded, the maximum adjustment value is set. At this point, an error
message is not displayed.

5-16

LI 5655 / LI 5660

5.8 DC Voltage Measurement (AUX IN)

5.8 DC Voltage Measurement (AUX IN)
The LI 5655 / LI 5660 is equipped with two connectors for DC voltage measurement on the rear panel.
1MΩ
AUX IN±42Vpeak（DC+AC）—＋

1MΩ
±42Vpeak（DC+AC）

AUX IN input circuit

The measurement voltage range is ±12 V and the display resolution is 0.001 V.
The sampling rate is 125 k samples/s, and the frequency bandwidth is approximately 5 kHz (-3 dB).
The maximum input voltage (non-destructive) is ±42 V between the center contact of the BNC connector
and the outer contact, and ±42 Vpeak (DC+AC) between the center contact and the enclosure, as well as
between the outer contact and the enclosure.
Ensure that the potential of the signal ground (outer contact) is the same as the enclosure potential (ground
potential) as much as possible.
If the potential of the signal ground (outer contact) exceeds the range of ±1 V from the enclosure potential
or fluctuates at a frequency exceeding 1 kHz, an additional error may occur.
If measurements fluctuate significantly, increase the smoothing time constant (narrow the bandwidth) to
reduce the fluctuations. However, this slows the response.
If the input voltage changes in a stepwise manner, the time it takes for the measured value to settle to99.9% of the final value is approximately 7 times the time constant.

The following shows how to measure the DC voltage.
First press the ＿DATA＿ key to go to the {Output Signal Setting Screen}.
{Output Signal Setting Screen}

DATA key(Operation screen
selection key)

5-17

LI 5655 / LI 5660

5.8 DC Voltage Measurement (AUX IN)

1) Display AUX{Basic Measurement Parameter Setting Screen}
Press the [ BASIC> ] soft key and then the[ AUX1-AUX2 ] soft key.
AUX1 and AUX2 are set in DATA1 and DATA2,
respectively. (Other settings are not changed.){Custom Measurement Parameter Setting Screen}
Press the [ CUSTOM> ] soft key and then the[ DATA1 ] soft key to select "AUX1" using the
MODIFY knob or up/down keys.
Press the [ DATA2 ] soft key to select "AUX1" or"AUX2" using the MODIFY knob or up/down keys.
(Other settings are not changed.)

2) Set the Smoothing Time ConstantFirst press the ＿AUX＿ key to go to the {Auxiliary I/O Setting Screen}.
{Auxiliary I/O Setting Screen}＿AUX＿ key
(Operation screen
selection key)

{Auxiliary Input Setting Screen}
Press the [ AUX IN> ] soft key from the {Auxiliary I/O
Setting Screen} to go to the {Auxiliary Input Setting
Screen}.
Then, to set the smoothing time constant for AUX IN1,
press the [ IN1 ] soft key to select the time constantusing the MODIFY knob or up/down keys.
To set the same for AUX IN2, press the [ IN2 ] soft key
Settable parameters

Current set

to perform the same operation.

value

5-18

LI 5655 / LI 5660

5.9 DC Voltage Output (AUX OUT)

5.9 DC Voltage Output (AUX OUT)
The LI 5655 / LI 5660 is equipped with two DC voltage output connectors on
the rear panel. The output impedance is approximately 1 kΩ.
The signal ground of the DC output voltage connector is connected to theenclosure.

First press the ＿AUX＿ key to go to the {Auxiliary I/O Setting Screen}.
{Auxiliary I/O Setting Screen}

AUX key(Operation screen
selection key)

{Auxiliary Output Setting Screen}

Press the [ AUX OUT> ] soft key from the {Auxiliary I/O
Setting Screen} to go to the {Auxiliary Output Setting
Screen}.
To set the output voltage value for AUX OUT1, press the[ OUT1 ] soft key to move through the digits using theleft/right cursor keys and then set the numerical value using
the MODIFY knob or up/down keys.
To set the same for AUX OUT2, press the [ OUT2 ] soft key

Setting range Current set value

to perform the same operation.
The output voltage range is ±10.500V and the resolution is
0.001 V.

！ CAUTION
Do not apply a voltage to the output connector from outside. The internal circuit may bedamaged.
There is an output current limit. Ensure that the load impedance is 1.1 kΩ or more.

5-19

LI 5655 / LI 5660

5.10 Supplying Power to the Preamplifier

5.10 Supplying Power to the Preamplifier
When you use a separately sold NF Corporation's preamplifier (LOW NOISE AMPLIFIER SA series), it isrecommended to use a recommended power supply (LOW NOISE DC POWER SUPPLY LP series, etc).
In general, a preamplifier and its power supply are more immune to external noise if they are installed near
the signal source. Lay the signal ground wires (reference potential) of the signal source and amplifier as
close to each other as possible to reduce the influence of common-mode noise, and amplify a signal andthen transmit it to make it more immune to the influence of noise.
If you do not need in particular a low noise, power can besupplied to the preamplifier from the PREAMP POWER
connector on the rear panel of the LI 5655 / LI 5660.
The power supply specification is ±15 V / 100 mA
max.
The potential of the 0 V line is the same as that of
Ground terminal for
guard(Enclosure ground)

2

3

4

the outer contact of the signal input connector.
Lay the power cable along the signal cable to reduce
the ground loop.

Pin numbers andconnections
1: +15V
2: 0V
3: -15V
4: 0V

1

Hirose HR10-7R-4S (73)Applicable Preamplifiers
The following preamplifiers were verified to work with the LI 5655 / LI 5660.
 WIDEBAND CURRENT AMPIFIER SA-600 series
 LOW NOISE AMPLIFIER SA-400 seriesThis information is valid at the time when this instruction manual was prepared. For the latest
information, consult with NF Corporation or one of our representatives.

！ CAUTION
Do not connect a device whose compatibility NF Corporation did not certify to the
PREAMP POWER connector. Otherwise, the connected device or the LI 5655 / LI 5660
may be damaged or injury may result.

5-20

LI 5655 / LI 5660

5.11 Setting Memory

5.11 Setting Memory
The LI 5655 / LI 5660 is equipped with 9 sets of setting memory. Frequently used settings can be stored in
the setting memory and recalled whey they are needed.
To save settings to the setting memory or recall them, first press the ＿UTIL＿ key to go to the {Utility
Screen}.
{Utility Screen}

UTIL key(Operation screen
selection key)1) Select the Setting Memory{Setting Memory Screen}

Press the [ MEMORY> ] soft key from the {Utility
Screen} to go to the {Setting Memory Screen}.
To select the setting memory, press the [ MEM No. ] soft
key to select a number from 0 to 9 using the MODIFY
knob or up/down keys.
Setting memory "0" stores the setting values (resume
memory) just before the power is turned off or shut off.
When the power is turned on, setting memory "0" isSelection range

Current setting

recalled.

2) Change the Setting Memory Name
{Setting Memory Screen}

To change the setting memory name, press the [ NAME ]soft key to move through the positions using theleft/right cursor keys and then set the memory name (1to 8 characters) using the MODIFY knob or up/down
keys.
Alphanumeric characters (A-Z, a-z, and 0-9) and somesymbols (#, @, -) can be used.
A change of name is applied immediately so there is no

Settable characters

Current setting

check work.

5-21

LI 5655 / LI 5660

5.11 Setting Memory3) Recall the Setting Memory{Setting Memory Recall Screen}
To recall the setting memory selected in the {Setting
Memory Screen}, press the [ RECALL> ] soft key. The
confirmation screen is displayed. To execute the recall,press the [ Exec ] soft key, and to cancel it, press the[ Cancel ] soft key.
The setting memory numbers to be recalled are 0 to 9.
Selected setting memory4) Save to the Setting Memory{Setting Memory Save Screen}
To save the setting to the setting memory selected in the{Setting Memory Screen}, press the [ SAVE> ] soft key.
The confirmation screen is displayed. To execute it,press the [ Exec ] soft key, and to cancel it, press the[ Cancel ] soft key.
The setting memory numbers to which the setting can besaved are 1 to 9.

5) Clear the Setting Memory{Setting Memory Clear Screen}
To clear the setting memory selected in the {Setting
Memory Screen}, press the [ CLEAR> ] soft key. The
confirmation screen is displayed. To execute it, press the[ Exec ] soft key, and to cancel it, press the [ Cancel ]soft key.
The setting memory numbers that can be cleared are
1 to 9.

5-22

LI 5655 / LI 5660

5.12 Other Functions

5.12 Other Functions
5.12.1 Disable the Panel Operation (KEY LOCK)
If you wish to disable the panel key and knob operations toprevent

misoperation, hold down the ＿ CLR ＿ key for at least 2 seconds in themeasurement screen to turn on the KEY LOCK lamp. Once the lamp turns on,
release the key immediately.
The front panel keys and knob cannot be operated while the KEY LOCK lamp is ON. However, they canbe used for the lamp-off operation and key lock and lamp-off cancellation.

5.12.2 Lamp Off (LAMP OFF)If you wish to avoid interference from ambient light in optical measurement, hold down the ＿CLR＿ key
for at least 2 seconds to turn on the KEY LOCK lamp and continue to hold it down for at least another 2
seconds to turn off all lamps and the display backlight. When they turn off, release the key. Both the key
lock and lamp-off are set to ON.
The lamp of the LAN connector on the rear panel also turns off in conjunction with the lamp-off.

 Key Lock and Lamp-off Cancellation (RELEASE)
Hold down the ＿CLR＿ key for at least 2 seconds in the lamp-off state to cancel both the key lockand lamp-off states. When the power is turned off and then on, both the functions are canceled.
 LOCAL Key (Remote Control)
Press the ＿CLR＿ key at remote mode (panel operation disable and REMOTE lamp ON) to restore
the local mode (panel operation enabled).
For details,  "LI 5655 / LI 5660 Instruction Manual (Remote Control)""2. Switching between remote / local states"

5-23

LI 5655 / LI 5660

5.12 Other Functions(Blank)5-24

LI 5655 / LI 5660

6． Dual Frequency Measurement

6.1 Overview of the Dual Frequency Measurement ................... 6-3
6.1.1 SINGLE (Single Frequency Measurement) .............................. 6-3
6.1.2 DUAL1 (Fractional Harmonic Mode) ........................................ 6-4
6.1.3 DUAL2 (Independent Frequency Mode) ................................... 6-5
6.1.4 CASCADE (Cascade Mode)..................................................... 6-6

6.2 Detection Mode Setting ......................................................... 6-7
6.3 Measurement Parameter Setting, Output, and Display(Dual frequency Measurement) ............................................ 6-8
6.4 Frequency Setting of the Internal Oscillator(Dual Frequency Measurement) .........................................6-10
6.5 Time Constant Filter Setting(Dual Frequency Measurement) ......................................... 6-11
6.6 Sensitivity Setting (Dual Frequency Measurement) ...........6-12
6.7 Phase Adjustment (Dual Frequency Measurement) ...........6-12
6.8 Measured Value Offset and Expansion(Dual Frequency Measurement) .........................................6-13
6.9 Ratio Measurement (Dual Frequency Measurement) ........6-14

6-1

LI 5655 / LI 5660

5.12 Other Functions

This chapter describes the dual frequency measurement (detection modes DUAL1, DUAL2, andCASCADE).
The same operations as those of the single frequency measurement (detection mode SINGLE) are omitted.
Before reading this chapter, read the description of the operations for the single frequency measurement(Chapters 4 and 5).

6-2

LI 5655 / LI 5660

6.1 Overview of the Dual Frequency Measurement

6.1 Overview of the Dual Frequency Measurement
The LI 5655 / LI 5660 is equipped with two dual-phase primary and secondary PSD (Phase-SensitiveDetector). This enables two frequency components included in a single input signal to be measured
simultaneously. The LI 5655 / LI 5660 has the following four detection modes, including the normal single
frequency measurement.
*1: C and HF connectors in the following sections are present only on the LI 5660.

6.1.1 SINGLE (Single Frequency Measurement)
Performs a normal single frequency measurement.
A signal component of a fundamental frequency (F) or fractional harmonic frequency (n x F / m) ismeasured, where F is the frequency of the reference signal. The secondary PSD is not used.

Primary PSD(Dual phase)

LPF

DC AMPAC AMPX

SIGNALINPUTYREF IN

PLL
Fp

×

n
m

INT OSC

Setting Frequency Range
Signal
input
A
A-B
1
C*
I

HF

*1

Primary PSD
Reference signal
sourceREF INSIN POSTTL POSTTL NEGINT OSC
SIGNALREF INTTL POSTTL NEGINT OSC

6-3

Primary frequency (Fp)range

0.3 Hz to 3.2 MHz

8 kHz to 11.5 MHz

LI 5655 / LI 5660

6.1 Overview of the Dual Frequency Measurement

6.1.2 DUAL1 (Fractional Harmonic Mode)
The primary and secondary PSD are connected in parallel.
The primary PSD can measure the signal component of the fractional harmonic frequency (n x F / m) andthe secondary PSD can measure the signal component of the harmonic frequency (n x F) simultaneously.
Primary

LPF

DC AMP
Xp

SIGNAL
INPUT

Yp
Fp

REF IN

PRI
n
×
m

LPF

PLL

DC AMPXs

Ys

INT OSC
SEC
(Fs)

×n

Secondary

Setting Frequency Range
Signal
input
A
A-B
1
C*
I

HF

*1

Primary PSD
Reference
signal source
REF INSIN POSTTL POSTTL NEGINT OSC
SIGNALREF INTTL POSTTL NEGINT OSC

Secondary PSD

Primary frequency(Fp) range

Reference
signal source

Secondary frequency(Fs) range

0.3 Hz to 3.2 MHz

Same with the primary PSD

8 kHz to 11.5 MHz■ Restrictions
The frequency range of the harmonic that can be measured is limited to the synchronous frequency
range of each input.
If the measurement signal (SIGNAL) is selected for the reference signal source, the PRI side isalways 1 / 1-fold and the SEC side is 1-fold regardless of the harmonic setting n or m.
■ Supplementary Explanation
Harmonic setting "n" is not the same in the primary and secondary PSD.
"n" and "m" of fractional harmonic (n x F / m) of the primary PSD are "PRI n" and "PRIm," respectively.
"n" of harmonic (n x F) of the secondary PSD is "SEC n."
They can be set individually.

6-4

LI 5655 / LI 5660

6.1 Overview of the Dual Frequency Measurement

6.1.3 DUAL2 (Independent Frequency Mode)
The primary and secondary PSDs are connected in parallel.
The primary PSD can measure the signal component of the primary frequency (Fp) and the secondary PSD
can measure the signal component of the secondary frequency (Fs) simultaneously.
REF IN, INT OSC, and SIGNAL can be selected for the reference signal to the primary PSD. However ,for the reference signal to the secondary PSD, only INT OSC can be selected.

Primary

REF INDC AMPLPF

SIGNAL
INPUT

Xp

Yp

PLL
Fp
DC AMPLPF

INT OSC

Xs

Ys
Fs

Secondary
INT OSC

Setting Frequency Range
Signal
input
A
A-B
1
C*
I

HF

*1

Primary detector
Reference
signal source
REF INSIN POSTTL POSTTL NEGINT OSC
SIGNALREF INTTL POSTTL NEGINT OSC

Secondary detector

Primary frequency(Fp) range

Reference
signal source

Secondary frequency(Fs) range

0.3 Hz to 3.2 MHzINT OSC

0.3 Hz to 3.2 MHz

8 kHz to 11.5 MHz

INT OSC

8 kHz to 11.5 MHz■ Supplementary Explanation
An external reference signal (synchronous frequency) input from REF IN is notsynchronized with the secondary frequency.
If the reference signal source that inputs into REF IN is synchronized with the 10 MHz
reference frequency, synchronization can be performed using the external 10 MHz
synchronization function.

6-5

LI 5655 / LI 5660

6.1 Overview of the Dual Frequency Measurement

6.1.4 CASCADE (Cascade Mode)
The primary and secondary PSDs are cascade-connected.
Detects a primary frequency signal using the primary PSD and detects that result with a secondary
frequency using the secondary PSD.
In CASCADE, The external reference signal (REF IN) is not connected to the primary PSD but to thesecondary PSD. Therefore, although REF IN and INT OSC can be selected for the reference signal to thesecondary PSD, only INT OSC can be selected for the reference signal to the primary PSD.

Primary

DC AMP

LPF

Xp
SIGNAL
INPUT
Yp
LPF

Fp

DC AMPXs

INT OSCREF INYs

PLLFs

Secondary

INT OSC

Setting Frequency Range
Signal
input
A
A-B
1
C*
I

1

HF *

Primary detector

Secondary detector

Reference
signal source

Primary frequency(Fp) range

INT OSC

0.3 Hz to 3.2 MHzINT OSC

8 kHz to 11.5 MHz

Reference
signal source
REF INSIN POSTTL POSTTL NEGINT OSCREF INSIN POSTTL POSTTL NEGINT OSC

Secondary frequency(Fs) range

0.3 Hz to 3.2 MHz

0.3 Hz to 3.2 MHz■ Restrictions
There are some restrictions on the cascade mode.
 The measurement signal (SIGNAL) cannot be selected for the reference signal source.
 If the HF *1 input is selected, the frequency range of the primary frequency (Fp) is
limited to 8 kHz to 11.5 MHz, and the frequency range of the secondary frequency (Fs)is limited to 0.3 Hz to 3.2 MHz.

6-6

LI 5655 / LI 5660

6.2 Detection Mode Setting

6.2 Detection Mode Setting
To select the detection mode, first press the ＿REF＿ key to go to the {Reference Signal Setting Screen}.
{Reference Signal Setting Screen} / PRI/SEC key(Simple operation key)

REF key(Operation screen selection key)
Current setting{Detection Mode Setting Screen}
Press the [ DET MODE> ] soft key from the {Reference
Signal Setting Screen} to go to the {Detection Mode
Setting Screen}.
Select the detection mode using the MODIFY knob or
up/down keys.
Press the [ Exec ] soft key to execute the setting.
Press the [ Cancel ] soft key to go back to the previous
Setting range
Current setting

screen.

If DUAL1, DUAL2, or CASCADE is selected forthe detection mode, the  / PRI/SEC key is / PRI/SEC key

enabled in the measurement screen.

(Simple operation key)Press the  / PRI/SEC key from themeasurement screen to switch between the(primary PSD) icon and(secondary PSD)

icon on the screen. The sensitivity (SENSE), time
constant (TC), and attenuation slope (SLOPE) of the PSD that is lit can be set.
However, the dynamic reserve setting is shared by the primary and secondary PSDs.

6-7

LI 5655 / LI 5660

6.3 Measurement Parameter Setting, Output, and Display (Dual frequency Measurement)

6.3 Measurement Parameter Setting, Output, and Display(Dual frequency Measurement)
The number of measurement parameter options that can be output and displayed is larger in the dual
frequency measurement than that in the single frequency measurement.

DATA key(Operation screen selection key) / DATA key(Simple operation key)1) Operation in the Measurement Screen
Measurement parameters are switched as follows using the  / DATA key only for DATA1 andDATA2.
DATA1 - DATA2: (before change)  Rp - θp  Xp - Yp  Xs - Ys  Xp - Xs  Rp - θp2) Operation in the Operation ScreenFirst press the _DATA_ key to go to the {Output Signal Selection Screen}.
{Output Signal Selection Screen}

Current DATA1, DATA2, DATA3, DATA4 output and display parameters (for DUAL1){Basic Measurement Parameter Setting Screen}
Next press the [ BASIC> ] soft key to display the basic
combination of soft keys.
The soft key display content is specified in DATA1 andDATA2.
Press the [ Xp-Yp ] soft key to set Xp in DATA1 and Yp
in DATA2.
Furthermore, DATA3 and DATA4 are not changed.

6-8

LI 5655 / LI 5660

6.3 Measurement Parameter Setting, Output, and Display (Dual frequency Measurement){Custom Measurement Parameter Setting Screen}
Press the [ CUSTOM> ] soft key to arbitrary set
parameters in DATA1 to DATA4.
To change the parameter in DATA1, press the [ DATA1 ]soft key and then select the measurement parameter using
the MODIFY knob or up/down keys.

Setting range

Current setting

The measurement parameters that can be set are as follows.
Output /display
DATA1
DATA2
DATA3
DATA4
Remark:X, Y, R, θsuffixSINGLE

Detection mode
DUAL1 DUAL2, CASCADE

X, R, AUX IN 1, NOISE

Xp,Rp,Yp, θp ,Xs, Rs,AUX IN 1, NOISE

Y, θ, AUX IN 1, AUX IN 2
X, R

Yp,θp,Xs,Rs, Ys,θs,AUX IN 1, AUX IN 2Y, θYp,θp,Xs,Rs, Ys,θsn: Harmonic order(n is added to the end
when the harmonic is set. Example:
Xn)

p: Primary PSD
s: Secondary PSD
n: Harmonic order (n is added to the end when the harmonic isset. Example: Xpn)

Xp,Rp,Yp, θp ,Xs, Rs■ Restrictions
 Measurement parameter settings are retained for each of detection modes SINGLE, DUAL1, and
DUAL2 (CACADE shares the settings with DUAL2).
 Only the primary PSD can measure the noise density.

6-9

LI 5655 / LI 5660

6.4 Frequency Setting of the Internal Oscillator (Dual Frequency Measurement)

6.4 Frequency Setting of the Internal Oscillator(Dual Frequency Measurement)
In detection modes DUAL2 and CASCADE, the frequency of the internal oscillator can be set individuallyfor the primary frequency and secondary frequency.
Furthermore, the frequency to output to the oscillator output (OSC OUT) can be selected for the primary
frequency and secondary frequency.

REF key(Operation screen selection key)1) Frequency Setting of the Internal Oscillator{Oscillator Setting Screen}First press the ＿REF＿ key to go to the {Reference Signal
Setting Screen}.
Next press the [ OSC SET> ] soft key to go to the{Oscillator Setting Screen}.

If the detection mode is SINGLE or DUAL1, use the internal oscillator[ FREQ> ] soft key, but if thedetection mode is DUAL2 or CASCADE, press the [ PRI FREQ> ] soft key to set the primary
frequency and press the [ SEC FREQ> ] soft key to set the secondary frequency.
If REF IN is selected for the reference signal, the [ PRI FREQ> ] soft key is not displayed in DUAL2
and the [ SEC FREQ> ] soft key is not displayed in CASCADE.
2) Output Selection of the Internal Oscillator{OSC Output Oscillator Selection Screen}

A signal synchronized with the internal connector can be
output from the OSC OUT connector.
Press the [ SEL CH> ] soft key to go to the {OSC Output
Oscillator Selection Screen}.
Select the output oscillator using the MODIFY knob or
up/down keys.
PRI: Synchronized with the primary frequency
SEC: Synchronized with the secondary frequency

6-10

LI 5655 / LI 5660

6.5 Time Constant Filter Setting (Dual Frequency Measurement)

6.5 Time Constant Filter Setting (Dual Frequency Measurement)
The time constant filters of the primary and secondary PSDs can be set individually.
To set the time constant, first press the _TC_ key to go{Time Constant Filter Setting Screen}

to the {Time Constant Filter Setting Screen}.
Press the [ PRI | SEC ] soft key to switch between the
primary PSD and secondary PSD settings. Configure thesetting for each PSD.
The procedure to select the filter (FILTER) and set thetime constant (TC) and attenuation slope (SLOPE) is the

PSD display

same as when the detection mode is SINGLE.

For details,  "4.6 Time Constant Filter Setting and Characteristics"
The PSD input offset adjustment setting is the same for both PSDs.
If the detection mode is CASCADE, a signal to transmit to the secondary PSD may be attenuateddepending on the time constant and attenuation slope settings on the primary PSD side. If the output signalof the secondary PSD cannot be detected, decrease the time constant and attenuation slope on the primary
PSD side.

6-11

LI 5655 / LI 5660

6.6 Sensitivity Setting (Dual Frequency Measurement)

6.6 Sensitivity Setting (Dual Frequency Measurement)
The sensitivity of the primary and secondary PSD is set individually.
To set the sensitivity, first press the _SENS_ key to go to the {Sensitivity Setting Screen}.
{Sensitivity Setting Screen}

Press the [ PRI | SEC ] soft key to switch between the
primary PSD and secondary PSD settings.
Configure the setting for each PSD.
The procedure to set the sensitivity (SENS) anddynamic reserve (DR) is the same as when the detection
mode is SINGLE.

PSD display

The dynamic reserve and auto sensitivity adjustment
settings are the same for both PADs.

For details,  "4.7 Sensitivity and Dynamic Reserve Setting"■ Restrictions
The sensitivity setting of the secondary PSD is lower in level than the sensitivity setting of the
primary PSD.
For example, if 100 mV is set for the sensitivity of the primary PSD, the sensitivity of the secondary
PSD is limited to less than 100 mV (50 mV, 20 mV, etc.).

6.7 Phase Adjustment (Dual Frequency Measurement)
The phase adjustment range of the primary and secondary PSDs is set individually.
To adjust the phase, first press the _PHASE_ key to go to the {Phase Adjustment Screen}.
{Phase Adjustment Screen}
Press the [ PRI | SEC ] soft key to switch between the
primary PSD and secondary PSD settings.
Configure the setting for each PSD.
The procedure to adjust the phase setting is the same as
when the detection mode is SINGLE.
PSD display

For details,  "4.8

6-12

Phase Adjustment"

LI 5655 / LI 5660

6.8 Measured Value Offset and Expansion (Dual Frequency Measurement)

6.8 Measured Value Offset and Expansion (Dual Frequency
Measurement)
The offset adjustment and expansion of the primary and secondary PSDs are set individually.
First go to each setting screen in the following procedure.
1) Offset Adjustment
First press the ＿DATA＿ key to go to the {Output Signal Setting Screen}.
{Offset Adjustment Screen}

Press the [ OFFSET> ] soft key to go to the {Offset
Adjustment Screen}.
Press the [ PRI | SEC ] soft key to switch between the
primary PSD and secondary PSD settings.
Configure the setting for each PSD.
The offset adjustment procedure is the same as when thedetection mode is SINGLE.

PSD display

For details,

 "5.1 Measured Value Offset and Expansion"2) Expansion
First press the ＿DATA＿ key to go to the {Output Signal Setting Screen}.
{Expansion Setting Screen}

Press the [ MATH> ] soft key to go to the {MathSelection Screen}. Select EXPAND using the MODIFY
knob or up/down keys to display the [ EXPAND> ] soft
key.
Press the [ EXPAND> ] soft key to go to the {Expand
Setting Screen}.
Press the [ PRI | SEC ] soft key to switch between the

Setting range

Current set value

primary PSD and secondary PSD settings. Configure thesetting for each PSD.

Press the [ RX ] or [ Y ] soft key to set the scale factor {x1｜x10｜x100} using the MODIFY knob or
up/down keys.
The expansion scale factor for measurement data R and X is shared and the expansion scale factor for Y
is set individually.
The apparent sensitivity (signal full scale) can be expanded 0.1 times or 0.01 times using EXPAND.

6-13

LI 5655 / LI 5660

6.9 Ratio Measurement (Dual Frequency Measurement)■ Restrictions
Only PSD outputs X, Y, and R (after X and Y offset adjustment) can be expanded. Other
parameters (phase, noise density, and AUX IN) cannot be expanded.
EXPAND is not executed while the normalize arithmetic processing or ratio arithmetic
processing is executed.

6.9 Ratio Measurement (Dual Frequency Measurement)
The denominator of the ratio arithmetic processing is always a primary PSD output (Xp, Yp, Rp). If thedetection mode is DUAL1 or DUAL2, secondary PSD{Ratio Setting Screen}

output (Xs) can be specified as the numerator, in addition
to the normal AUX IN.
First press the ＿DATA＿＿ key to go to the {Measurement
Data Setting Screen}.
Press the [ MATH> ] soft key to go to the {MathSelection Screen}. Select RATIO using the MODIFY
knob or up/down keys to display the [ RATIO> ] soft key.

Setting range

Current setting

Press the [ RATIO> ] soft key to go to the {RATIO
Setting Screen}.

Press the [ RATIO ] soft key to select a RATIO arithmetic expression using the MODIFY knob or up/down
keys.
RATIO
selection
RATIO1RATIO2

Contents of arithmetic expression
K×（primary PSD（Xp，Yp，Rp） ÷ AUX IN1）[%FS]

K×（secondary PSD（Xs，Ys，Rs） ÷ AUX IN1）[%FS]

K×（primary PSD（Xp，Yp，Rp）÷ secondary PSD Xs） [%FS]

Detection
mode
SINGLE
DUAL1
DUAL2
CASCADE
DUAL1
DUAL2

The maximum update rate of the numerator is 10 k samples/s.
However, it may slow down depending on the internal processing.

6-14

LI 5655 / LI 5660

7． Troubleshooting

7.1 Error Message ....................................................................... 7-2
7.1.1 Power-On Errors ...................................................................... 7-3
7.1.2 Panel Operation Errors ............................................................. 7-3
7.1.3 Errors During Measurement ..................................................... 7-4
7.1.4 Signal Overload ........................................................................ 7-5
7.1.5 Loss of Synchronization ........................................................... 7-5

7.2 Troubleshooting..................................................................... 7-6
7.3 Q & A ..................................................................................... 7-7

7-1

LI 5655 / LI 5660

7.1 Error Message

7.1 Error Message
This chapter describes the errors that can occur during power-on self testing, panel operations and major
errors that may occur in the normal course of measurement, with their causes and necessary remedies.
If repair is required, contact NF Corporation or one of our representatives.
When requesting repair of the LI 5655 or LI 5660, please let us know the contents of any error messages
that may be displayed.
Rare events such as malfunctions due to strong external noise may cause error messages not described inthis manual to be displayed.
Unusual operations such as firmware updates may cause error messages not described in this manual to be
displayed. If other manuals have been provided, refer to them as well.
See the " LI 5655 / LI 5660 Instruction Manual (Remote Control)" for errors that only occur with remotecontrol. Remote control-related errors display a message box like the following. These error messages
automatically disappear after a few seconds.

Error Message (Example)

7-2

LI 5655 / LI 5660

7.1 Error Message

7.1.1 Power-On Errors
If an error occurs during power-on self testing, the following error message is displayed on the startup
screen.
Error Message
Error No.-510
Backup Memory…Initialized
Calibration...Uncalibrated

Contents and Cause
Initialization occurs when resume
memory contents have been lost.

RemedyTurn power off and back on.
If the error recurs, a fault ispresent requiring repair.

Calibration data has been lost.

A fault is present requiring repair.

Error Display Screen Example

7.1.2 Panel Operation Errors
Errors displayed regarding panel operations are as follows.
Error Message
Error No.-206
Auto-once failed
due to unlock

Contents and CauseUNLOCK interrupted automatic
setting execution.
Affected Automatic Settings_AUTO_ →[ MEASURE ]_AUTO_ →[ SENS ]_AUTO_ →[ PHASE（PHASE PRI） ]_AUTO_ →[ PHASE SEC ]_DATA_ →[ OFFSET> ]→[ AUTO once ]Error No.-207
X, Y out of range

Error No.-208
DC compensation
value saturation
occurredError No.-330

The X or Y measurement value is outof range for adjustment, so automatic
offset adjustment cannot be
performed.
PSD Adj out of automatic adjustment
range.
(Occurred only in AUTO once of PSD
Adj)Failure occurred in self-test results.

Self-test error

7-3

RemedyCheck that the reference signal
frequency and amplitude arenormal and not indicating
UNLOCK on the measurement
screen.

Increase the sensitivity (signal fullscale). Or attenuate the input
signal.
Execute it as a no-signal
condition.
If the error recurs, a fault may bepresent. Contact with NF
Corporation or one of ourrepresentatives.
Check connections and retry
self-test.
If the error recurs, a fault may
be present. Contact with NF
Corporation or one of ourrepresentatives.

LI 5655 / LI 5660

7.1 Error Message

7.1.3 Errors During Measurement
Errors that may be displayed during measurement are as follows.
Error Message
Error No.-381
Overheat

Contents and Cause
The chassis is overheated.

Remedy1) Ambient temperature is high.
2) Cooling fan failure.

Error No.-382
Line over voltage

Power source overvoltage detected.

Error No.-383
Internal
communicationerror

An internal communication error
occurred.

1) Move to a cooler location orprovide more ventilation.
Turn the power off and wait
for the internal temperature tonormalize before turning
power back on.
2) Ask NF Corporation or one of
our representatives for repair.
Turn off the power and check thatvoltage at the power outlet iswithin the voltage range of thisproduct. Also make sure thepower voltage selection switch is
set correctly before turning backon.
Turn power off and back on. If
the error recurs, a fault is present
requiring repair.

The above error messages remain displayed. Key-lock and lamp-off are canceled, but panel and remote
operations are ignored and the screen does not update.
Turn the power off and apply the remedy.

The internal communication
error appears on all screens.

Error Display Screen Example

7-4

LI 5655 / LI 5660

7.1 Error Message

7.1.4 Signal Overload
If an excessive signal level is detected anywhere on the signal path from input to output and measurement
is impossible, an icon is displayed in the screen.
For details,  "4.7.3 Signal Over-level Display and Monitor Output"
Over-level
StatusPROTECT

IN/OUTINPUTOUTPUT

AUX

Description

RemedyVoltage exceeding the maximum input
voltage was detected in the A or B
connector.
Both the A and B connectors areinternally separated temporarily forprotection.
Both events described in INPUT and
OUTPUT below occurred.
Over-level occurred in the AC
amplification part from the signal input
connector to primary PSD input.
The PSD input signal can be checked with
the MONITOR OUT connector.

Lower the signal level applied to the A
or B connector.
Use the C connector. (For the LI 5660
only)Over-level occurred in the signal
processing part of the PSD output (timeconstant filter and DC amplification part).
The output voltage allowable range wasexceeded as a result of an OFFSET,EXPAND, NORMALIZE, RATIO, orother arithmetic processing.
Measurement parameters that are not
output and displayed are also included in
the scope.
Excessive input into the AUX IN 1 or
AUX IN 2 connector.

(See below)
Increase the sensitivity (signal fullscale).
Increase the dynamic reserve.
If a DC component is included in the
input signal, use the AC coupling.
Set the line filter to ON to attenuate
the noise coming from the power
supply.
Increase the time constant andattenuation slope to attenuate thenoise.
Increase the sensitivity (signal fullscale).
Cancel the arithmetic processing andcheck the original signals (X, Y, R,
AUX IN 1). Then configure the setting
again so the output does not exceed the
maximum level.
Lower the signal level applied to the
AUX IN 1 or AUX IN 2 connector.

When more than one event occurs at the same time, their display priority status is according to the abovetable.

7.1.5 Loss of Synchronization
If the external reference signal or measurement signal is set for the reference signal source and they are notsynchronized, the UNLOCK status is displayed in the measurement screen.
In such cases, check the waveform selection of the external reference signal, and that the actual reference
signal amplitude, waveform and frequency are within the range of synchronization.
For details,  "4.4

Reference Signal Setting and Connection", "9.3

Reference Signal System"

If synchronization does not occur with a reference signal that is within the specified range and without
noise or instability, ask us or our agent for repair.

7-5

LI 5655 / LI 5660

7.2 Troubleshooting

7.2 Troubleshooting
If you suspect a problem, check the following list for a solution at once. If the problem is not resolved orremains unchanged after applying the suggested remedy, contact us or our agent.
Table 7-1 In case of suspected anomaly
Description
Power cannot be
turned on

Possible Cause
Bad power cord connection.

Securely plug in the power cord.

The power source is out of the
rated range.

Use a meter or other method to check the voltage at
the power outlet.
Check the setting of the line voltage selector switch
on the rear. Be sure the power cord is unplugged
when changing the setting of the line voltage
selector switch.
Unplug the power cord and after checking that thesource voltage matches the setting of the line
voltage selector switch, replace the fuse. Even
though the fuse has blown, because it indicates a
failure, ask us or our agent for repair.
If the KEY LOCK lamp is lit,press and hold the CLR key until themeasurement screen disappears and then reappears.
Release the key when the screen reappears. The
KEY LOCK lamp turns off and panel operation isrestored.
If the REMOTE lamp is lit, press
the CLR /LOCAL key to re-enable local control.

The fuse is blown.

Panel Operation
Disabled

RemedyThe keys are locked.

Remote control is enabled.

In the Local Lock Out state, this operation isdisabled. Use the external controller to re-enablelocal control.
If the instructions
do not work as
described

Settings are not initialized.

Cooling fan sound The fan may be faulty or
deteriorated.
increased

Many descriptions presume settings have been
initialized. Try again after initializing by pressing
the UTIL , [RESET>], [Exec] key sequence.
Ask NF Corporation or our agents for repair.

7-6

LI 5655 / LI 5660

7.3 Q & A

7.3 Q & A
Q1. I want to measure the peak voltage of the pulse signal.
Do the lock-in amplifier voltage V units represent Vpeak?
A1. The lock-in amplifier cannot measure peak values.
This instrument measures the effective value (Vrms) of the fundamental wave component ofrepetitive signals.
When measuring a pulse signal with the lock-in amplifier, the measured value depends on the pulse
waveform characteristics (such as peak value, pulse width and duty cycle). If the waveformcharacteristics are already known, the peak value can be calculated from the effective value,
although if the duty cycle is low, the S/N (signal-to-noise ratio) is low because the majority of theperiod has no signal (mostly noise). Also isolated one-shot pulse signals cannot be measured.
Q2. I want to view the signal waveform. Is it possible to reproduce the waveform buried in noise?
A2. The lock-in amplifier cannot display waveforms.
If the signal continuously repeats, a rough waveform might be compounded from the measured
fundamental wave and harmonic components, but we do not recommend this because of thelikelihood of large errors. Especially at high frequency, a correct waveform cannot be obtained
because of high harmonic phase shift.
Q3. Can DC voltage be measured?
A3. The lock-in amplifier cannot measure DC signal.
Only AC signals can be measured. When changed to AC signals by amplitude modulation, DC
signals can be measured. However in this case modulator gain must be calibrated.

7-7

LI 5655 / LI 5660

7.3 Q & A(Blank)7-8

LI 5655 / LI 5660

8． Maintenance

8.1 Preface .................................................................................. 8-2
8.2 Daily Maintenance................................................................. 8-3
8.3 Storage, Repacking, and Transportation .............................. 8-3
8.4 Version Confirmation ............................................................. 8-4
8.5 Main Function Confirmation .................................................. 8-5
8.5.1 Self Test.................................................................................... 8-5

8.6 Performance Test .................................................................. 8-6
8.6.1 Preface ..................................................................................... 8-6
8.6.2 Isolation Confirmation ............................................................... 8-8
8.6.3 Voltage Measurement Accuracy ............................................. 8-10
8.6.4 Current Measurement Accuracy ............................................. 8-16
8.6.5 Analog Output Voltage Accuracy of Measured Values............ 8-18
8.6.6 Common Mode Rejection Ratio .............................................. 8-20
8.6.7 Input referred noise. ............................................................... 8-21
8.6.8 Phase Accuracy...................................................................... 8-22
8.6.9 Frequency Accuracy ............................................................... 8-24
8.6.10 Amplitude Accuracy of Internal Oscillator Sine
Wave Output .......................................................................... 8-25
8.6.11 AUX IN DC Voltage Measurement Accuracy .......................... 8-26
8.6.12 AUX OUT RMS Voltage Accuracy .......................................... 8-27

8.7 Calibration ...........................................................................8-28
8.8 Maintenance Information.....................................................8-29

8-1

LI 5655 / LI 5660

8.1 Preface

8.1 Preface
The following maintenance tasks are required to keep the instrument in top operating condition.
 Operation Inspection

Check whether the instrument operates correctly.

 Performance Test

Check whether the instrument satisfies the specified
ratings.

 Adjustment and Calibration

If the ratings are not satisfied, adjustment and calibration
are performed by NF Corporation to recover proper performance.

 Fault Repair

If performance is not improved, NF Corporation checks thecause and location of the fault, and repair.

This manual describes basic operation checking and performance testing procedures.
For advanced inspection, adjustment, calibration and fault repair, contact NF Corporation or our agent.

！ WARNING

There are high voltage parts inside this device. Never remove the cover.
No one except trained service technicians who have knowledge of hazard prevention is
authorized to check the inside of this device.

8-2

LI 5655 / LI 5660

8.2 Daily Maintenance

8.2 Daily MaintenanceInstall the LI 5655 / LI 5660 in a location that satisfies the installation conditions.
For details,  "2.2.2 Installation Conditions".
The front panel of the LI 5655 / LI 5660 is made of plastic. Avoid damage from contact with sharp or hot
objects.
When the panel or case needs cleaning, wipe with a soft cloth. To remove persistent contamination, wipewith a soft cloth soaked with neutral detergent and wrung out. Do not use any organic solvents like thinner
or benzene, or any chemical cleaning cloth, as they may cause the surface finish to deteriorate, tarnish, orcome off.

8.3 Storage, Repacking, and Transportation
Store the LI 5655 / LI 5660 in a location that satisfies the installation conditions.
For details,  "2.2.2 Installation Conditions".
When repacking for transport, use a carton with adequate strength and enough space for sufficient padding
to withstand the weight and protect the instrument.
During transport, handle with care to avoid strong impact.

8-3

LI 5655 / LI 5660

8.4 Version Confirmation

8.4 Version Confirmation
The same model products may have different version numbers due to functional improvements and fault
repairs. Behavior can differ according to version, so if an anomaly is detected, provide us with the version
information along with the symptoms.
Our website may provide guidance for updating the firmware.
After startup, the version information can be confirmed by the following procedure.
First, press the ＿UTIL＿ key to move to the {Utility Screen}.
{Utility Screen}＿UTIL＿ key(Operation Screen
Selection Keys){System Setting Screen}
Press the [ SYSTEM> ] soft key to go to the{System Setting Screen}.
Press the [VERSION>] soft key to go to the{Version Information Screen}.

{Version Information Screen}FW: Firmware version

Cal: Last calibration date

FPGA

: FPGA version

IF: Interface version

BOARD : Board version

To return to the top level operating screen, press
SCRN / EXIT.

8-4

LI 5655 / LI 5660

8.5 Main Function Confirmation

8.5 Main Function Confirmation
Before performance testing, check the basic operation of the LI 5655 / LI 5660 by referring to"2.4 Simplified Operation Check".

8.5.1 Self Test
To execute self testing of the LI 5655 / LI 5660, move to the {Self Diagnosis Screen}.
{Self Diagnosis Screen}First, press the ＿UTIL＿ key to move to the {Utility
Screen}, then press the [SYSTEM>] soft key to go
to the {System Setting Screen}, then press the[SELF TEST>] soft key to go to the {SelfDiagnosis Screen}.

BNC Cable (1 m)
Connect the OSC OUT and the "A"of SIGNAL INPUT with a BNC cable (1 m).
Press the [Exec] soft key on the {Self Diagnosis Screen} to execute the self test.
Allow several tens of seconds for the self test.

8-5

LI 5655 / LI 5660

8.6 Performance Test

8.6 Performance Test
8.6.1 Preface
A performance test is performed as part of preventative maintenance to prevent performance deteriorationof the LI 5655 / LI 5660.
A performance test is conducted when necessary to verify performance during acceptance inspection,
periodic inspection and after repair.
The simple performance test described here is performed using commercially available standards andmeasurement instruments. For advanced testing, ask NF Corporation or one of our agents. We handle
requests for a fee.
If the specifications are not satisfied after a performance test, calibration or repair. Contact with NF
Corporation or one of our agrents.
1) Test environment confirmation
Conduct performance testing in the following environment.
- Ambient temperature: 23 ±5°C- Ambient humidity: 20 to 70% RH, non-condensing- Power supply voltage: 100 or 120 V AC ±10%, or 230 V AC +10%, –14%

- Warm-up time

: At least 30 minutes2) Test preparation
Before a performance test, initialize the settings.
To initialize the settings, press the _UTIL_ key, [RESET>] soft key, and the [Exec] soft key, in that order.
For details,  "4.2 Simple Operation Procedure for Using the Device for the First Time"8-6

LI 5655 / LI 5660

8.6 Performance Test

3) Needed equipment
The following measurement equipment is required for operation inspection and performance testing.
Name
Required Capability
Example Model
Generator
Waveform:
Sine wave
WF1947Frequency: 0.5 Hz to 11 MHz(NF Corp.)
Amplitude: 100 mVrms to 7 Vrms
TTL output synchronized with sine wave
Digital Multi Meter
AC Voltmeter (true rms)
34401A(DMM)(100 mV to 10 V range)(Keysight)
Accuracy: ±0.1% (10 Hz to 20 kHz)DC Voltmeter(100 mV to 100 V range)
Accuracy: ±0.04%
Ohmmeter(100 kΩ range [10 μA])
(100 Ω range [1 mA])
Accuracy: ±0.05%
RMS Voltmeter(100 mV to 10 V range)
URE3(true rms)
Frequency response correction should be (Rohde & Schwarz)
enabled.
Accuracy: ±0.5% (to 100 kHz)Accuracy: ±0.7% (to 1 MHz)
Accuracy: ±1% (to 3 MHz)
Accuracy: ±4% (to 11 MHz)
Frequency Counter
Accuracy : ±10 ppm,
53131A
Resolution : 1 ppm or higher(Keysight)
Oscilloscope
Bandwidth: at least 10 MHz and 10 s/div
GDS2842(NF Corp.)
Others
BNC Cable
50 Ω, BNC, RG58/U equiv.
Alligator Clip Cable
BNC-Alligator Clip Cable, and others
Terminator
50 Ω, BNC
Shorted Plug
BNC
Divider
BNC, T-type
Power Splitter
BNC, 50 Ω, 2-way

8-7

LI 5655 / LI 5660

8.6 Performance Test

8.6.2 Isolation Confirmation
Confirm the floating function of the signal input section.
In the following setting descriptions, LI 56xx represents both the LI 5655 and LI 5660.
1) Floating resistance confirmation
LI 56xx settings
Measurement instrument
settings
Connections

Measurement method
Judgment (Pass Range): Set the signal ground to FLOAT.
: Set the DMM to resistance mode.
Set the measurement range to 100 kΩ (test current 10 μA or less).
: Connect the HOT side of the DMM to the COLD side of the signal
input connector (e.g., A). Connect the COLD side of the DMM tochassis ground (e.g., COLD side of MONITOR OUT).
: Measure the DC resistance between HOT and COLD sides of the
DMM.
: DC resistance = 8 kΩ to 11 kΩ (about 9.6 kΩ)2) Ground resistance confirmation
LI 56xx settings
Measurement instrument
settings
Connections

Measurement method
Judgment (Pass Range): Set the signal ground to GND.
: Set the DMM to resistance mode.
Set the measurement range to 100 Ω (test current 10 mA or less).
: Connect the HOT side of the DMM to the COLD side of the signal
input connector (e.g., A). Connect the COLD side of the DMM tochassis ground (e.g., COLD side of MONITOR OUT).
: Measure the DC resistance between HOT and COLD sides of the
DMM.
: DC resistance = 10 Ω to 13 Ω (about 11 Ω)








DigitalMulti Meter
9.972 k







8-8

LI 5655 / LI 5660

8.6 Performance Test

3) Clamp diode confirmation
LI 56xx settings

Measurement instrument
settings
Connections

Measurement method
Judgment (Pass Range): Set the signal ground to FLOAT.
Display AUX1 for DATA1.
AUX OUT1 is +10 V and -10 V: ―――: Connect the HOT sides of AUX IN1 and AUX OUT1 to the COLD
side of the signal input connector (ex. A). Connect the COLD sides of
AUX IN1 and AUX OUT1 to chassis ground (eg., COLD side of
MONITOR OUT).
: With AUX OUT1 set to +10 V or –10 V, read the DATA1 (AUX IN1)
measurement value (displayed).
: AUX IN 1 measured value ＝ +1.2 V to +1.6 V (about +1.4 V), and–1.6 V to –1.2 V (about –1.4 V)

BNC - Alligator Clips Cable

8-9

LI 5655 / LI 5660

8.6 Performance Test

8.6.3 Voltage Measurement Accuracy
The following method cannot be used to test very small signal measurement accuracy. As testing very small
signal measurement accuracy requires a separate precision attenuator, contact NF Corporation or our agent.
The lock-in amplifier measures only fundamental frequency component. In contrast, general-purpose
standard voltmeters measure effective (rms) values that include harmonic distortion and noise. Therefore,
sufficient measurement accuracy cannot be obtained at low voltage.
In the following setting descriptions, LI 56xx represents both the LI 5655 and LI 5660. Also,
the LI 5660 is shown in the connection diagrams.
*1: Only the LI 5660 is equipped with the C and HF connectors.
1) Input A
LI 56xx settings: Use connector A for signal input, and set the input coupling to AC.
Set the signal ground to FLOAT.
Use INT OSC (internal oscillator) as the reference signal source.
Set the DR setting to LOW.
Set the time constant to 100 ms.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Set measurement parameter DATA1 to R.
Frequency, amplitude and sensitivity are per the following table.
Measurement: For 100 kHz or less, use the DMM in AC voltage mode.
instrument settings
For 100 kHz to 3 MHz, use a RMS Voltmeter.
Connections: Connect a BNC cable from one side of a divider at the LI 56xx
OSC OUT connector to connector A. Connect a BNC cable fromthe other side of the divider to the DMM.
Measurement method : Select the following specified frequencies, amplitudes and sensitivities,
and read the measurement values at DATA1 and the DMM (or RMS
Voltmeter).
Judgment (Pass Range) : Per the following table.

BNC Cable (1 m)
DividerDMM
or RMS Voltmeter
0.9921 V AC

BNC Cable (1 m)
BNC-Banana
Conversion Adapter

8-10

LI 5655 / LI 5660

8.6 Performance Test

Judgment
Frequency

Sensitivity (rms)

INT OSC
Amplitude
Setting (rms)

1V

1V

500 mV

500 mV

R/S

Pass Range(R/S)_.____V_.____V

20 kHz
200 mV

R: Measured Value (rms)
S: Voltmeter Reading (rms)

200 mV

100 mV

100 mV

1V

1V

500 mV

500 mV

200 mV

200 mV

100 mV

100 mV_.____ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV

0.995 to
1.005

_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV

50 kHz_.____ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV

0.99 to 1.01_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV

1V

1V

200 mV

500 mV

100 mV

200 mV

100 mV

100 mV_ _ _ . _ mV

100 kHz_.____ _ _ . _ mV
_ _ _ . _ mV_.___

0.98 to 1.02

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV_.____.____V

1V

1V

500 mV

500 mV

200 mV

200 mV

100 mV

100 mV_.____V

1 MHz

_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

0.97 to 1.03

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV_.____.____V

1V

1V

500 mV

500 mV

200 mV

200 mV

100 mV

100 mV_.____V

3 MHz

8-11

_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

0.95 to 1.05

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

LI 5655 / LI 5660

8.6 Performance Test
2) Input C*1
LI 56xx settings

Measurement
instrument settings
Connections

Measurement method

Judgment (Pass Range): Use connector C for signal input.
Set the signal ground to FLOAT.
Use REF IN (external reference signal) for the reference signal source.
Select the TTL+ reference signal waveform.
Set the DR setting to LOW.
Set the time constant to 100 ms.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Set measurement parameter DATA1 to R.
Frequency, amplitude and sensitivity are per the following table.
: For 100 kHz or less, use the DMM in AC voltage mode.
For 100 kHz to 3 MHz, use a RMS Voltmeter.
Set the generator to sine wave.
: Connect the BNC cable from the generator synchronous output (SYNC
OUT) connector to the LI 56xx REF IN connector. :Connecta
BNC cable from one side of a divider at the generator output connector
to connector C. Connect a BNC cable from the other side of the divider
to the DMM.
: Select the following specified frequencies, amplitudes and sensitivities,
and read the measurement values at DATA1 and the DMM (or RMS
Voltmeter).
: Per the following table.

Generator

BNC Cable (1 m)

1.00000 kHz
1.000 Vrms
FUNC OUT SYNC OUTDMMor RMS Voltmeter

Divider

BNC Cable (1 m)

BNC Cable (1 m)

0.9921 V AC

BNC-Banana
Conversion Adapter

8-12

LI 5655 / LI 5660

8.6 Performance Test

Judgment

Frequency

Sensitivity (rms)

Generator(no load)
Amplitude Setting
(rms)

10 V

7V

5V

_.____V

1V

1V

10 V

7V

5V

_.____V_.____V

1V

1V

10 V

7V

5V

5V

_.____V

2V

1V

1V

10 V

7V

5V

5V

_.___V

2V

1V

1V

10 V

7V

5V

5V

_.___V

2V

1V

1V

_.___
_.___
_.___

_.___V_.___V

0.99 to 1.01_.____.___V_.___V_.____.___V_.___V_.____.___V_.___V_.___

0.98 to 1.02_.___V_.___V_.____.____V_.____V_.____.___V_.___V_.____.___V_.___V_.___

0.97 to 1.03_.___V_.___V_.____.____V_.____V_.____.___V_.___V_.____.___V_.___V

3 MHz
2V

_.___

_.___V

1 MHz
2V

0.995 to1.005_.___V

100 kHz
2V_.____.____V

5V
2V

_.___

_.____V

50 kHz2V

Pass Range(R/S)_.____V

20 kHz2V

R/S_.____V

5V

2V

R: Measured Value (rms)
S: Voltmeter Reading (rms)_.___0.95 to 1.05_.___V_.___V_.____.____V_.____V

8-13

_.___

LI 5655 / LI 5660

8.6 Performance Test
13) Input HF *LI 56xx settings

Measurement
instrument settings
Connections

Measurement method

Judgment (Pass Range): Use the HF connector for signal input.
Set the signal ground to FLOAT.
Use REF IN for the reference signal source.
Select the TTL+ reference signal waveform.
Set the DR setting to LOW.
Set the time constant to 100 ms.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Set measurement parameter DATA1 to R.
Frequency, amplitude, sensitivity and input impedance are per thefollowing table.
: Use the RMS Voltmeter.
Set the generator to sine wave.
: Connect the BNC cable from the generator synchronous output (SYNC
OUT) connector to the LI 56xx REF IN connector. :Connecta
BNC cable from one side of a divider at the generator output connector
to connector HF. Connect a BNC cable from the other side of thedivider to the DMM.
When the input impedance is set to 50 Ω, connect a 50 Ω terminator to
the RMS Voltmeter. Also, use a Power Splitter in place of the divider.
: Select the following specified frequencies, amplitudes, sensitivities andinput impedances, and read the measurement values at DATA1 and the
RMS Voltmeter.
: Per the following table.

Generator

BNC Cable (1 m)

1.00000 kHz
1.000 Vrms
FUNC OUT SYNC OUTBNC Cable (1 m)
RMS Voltmeter
0.9921 V AC*

BNC Cable (1 m)

DividerWith the 50 Ω setting, use a Power Spliter

When the LI 56xx is set to 50 Ω,
install a 50 Ω terminator at the
RMS Voltmeter.

8-14

LI 5655 / LI 5660

8.6 Performance Test

Judgment
Frequency(Zin)

Sensitivity (rms)

Generator(no load)
Amplitude Setting
(rms)

1V

1V

500 mV

500 mV_.____V

200 mV

100 mV

100 mV

1V

1V

500 mV

500 mV
200 mV
100 mV

1V

3V

500 mV

1.5 V

_.___

0.97 to 1.03

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV

_.___
_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

0.95 to 1.05

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV_.____V

600 mV

100 mV

300 mV

1V

3V

500 mV

1.5 V

_.___
_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

0.93 to 1.07

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV_.____.____V_.____V11MHz（50 Ω）

100 mV_ _ _ . _ mV_.____V

10MHz(50 Ω)

200 mV_.____ _ _ . _ mV_.____V

100 mV

200 mV

Pass Range(R/S)_.____V3MHz(1 MΩ)
200 mV

R/S_.____V

1MHz(1 MΩ)
200 mV

R: Measured Value (rms)
S: Voltmeter Reading (rms)

600 mV
300 mV

8-15

_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

0.86 to 1.14

_ _ _ . _ mV
_ _ _ . _ mV_.___

_ _ _ . _ mV
_ _ _ . _ mV_.___

LI 5655 / LI 5660

8.6 Performance Test

8.6.4 Current Measurement Accuracy
LI 56xx settings: Use connector I for signal input.
Set the input coupling to DC.
Set the signal ground to FLOAT.
Use INT OSC as the reference signal source.
Set the DR setting to LOW.
Set the time constant to 200 ms.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Set measurement parameter DATA1:R.
Frequency, amplitude, sensitivity and current input conversion
gain are per the following table.
: Set the DMM to AC voltage mode.

Measurement
instrument settings
Connections

Measurement method

Judgment (Pass Range): Connect a BNC cable from one side of a divider at the LI 56xx
OSC OUT connector via the V-I conversion jig to connector I.
Connect a BNC cable from the other side of the divider to the
DMM.
: Select the following specified frequencies, amplitudes,
sensitivities and current input conversion gains, and read themeasurement values at DATA1 and the DMM.
: Per the following table.

BNC Cable (1 m)
Divider
DMM
0.9921 V AC

V-I Conversion Jig:
Uses a resistor of precisely known value.
To suppress noise, keep the resistor in a shielded casewith the BNC connectors.
・Prepare a 1 MΩ resistor for 1 M conversion gain.
・Prepare a 100 MΩ resistor for 100 M conversion gain.

8-16

BNC Cable (1 m)
BNC-Banana
Conversion Adapter

LI 5655 / LI 5660

8.6 Performance Test

Judgment
Sensitivity (rms)
Conversion
Gain

Frequency

1 μA
1M

1 kHz

INT OSC
Amplitude Setting(rms)

P: Jig Resistance Value
R: Measured Value (rms)
S: Voltmeter Reading (rms)_ . _ _ _ _ MΩ

1V_._____.____

10 nA
100M

P × R/S

Pass Range(P × R/S)

μA
V

0.99 to 1.01_.___

_ _ _ . _ _ MΩ
125 Hz1V__.____.____

0.99 to 1.01

nA
V

_.___

If, for example, the available accuracy of the 100 MΩ resistor is ±1%, the pass range is
expanded to 0.98 to 1.02, and judgment is an approximation. To improve accuracy, use
a 10 MΩ resistor instead of 100 MΩ, and use 1/10th of the LI 56xx INT OSC amplitudesetting. In this case, because the LI 56xx effective input impedance is about 100 kΩ, thepass range is 0.98 to 1.00 and the judgment is an approximation.

8-17

LI 5655 / LI 5660

8.6 Performance Test

8.6.5 Analog Output Voltage Accuracy of Measured Values
LI 56xx settings: Use connector A for signal input.
Set the input coupling to AC.
Set the signal ground to FLOAT.
Use INT OSC (internal oscillator) as the reference signal source.
Set the frequency to 1 kHz and amplitude to 0 V (rms).
Set the sensitivity to 1 V (rms) and DR setting to LOW.
Set the time constant to 100 ms.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Set measurement parameter DATA1 to X, DATA2 to Y, DATA3
to X and DATA4 to Y.
Turn on the offset function for both X and Y.
: Set the DMM to DC voltage mode.

Measurement
instrument settings
Connections: Connect a shorted plug (or 50 Ω terminator) to connector A of the
LI 56xx.
Connect the LI 56xx DATA OUT1 to 4 connectors to the DMM
with a BNC cable.
: With the offset value set to +100%, 0% and –100%, read themeasurement value on the DMM for each DATA OUT connector.
: Per the following table.

Measurement method
Judgment (Pass Range)

Measurement method
Judgment: Per the following table.

SHORT
PLUG
DMM
9.9999 V DC

BNC Cable
BNC-Banana
Conversion
Adapter

8-18

LI 5655 / LI 5660

8.6 Performance Test

Judgment

Offset Value
+100%
0%
-100%

DMM Reading
Pass Range (±10.040 V at ±100%, ±10 mV at 0%)
DATA1
DATA2
DATA3
DATA4
(X)
(Y)
(X)
(Y)
+__.___V+__.___V+__.___V+__.___V_ _ _ . _ _mV_ _ _ . _ _ mV
_ _ _ . _ _ mV
_ _ _ . _ _ mV-__.___V-__.___V-__.___V-__.___V

8-19

LI 5655 / LI 5660

8.6 Performance Test

8.6.6 Common Mode Rejection Ratio
LI 56xx settings: Use connector A-B for signal input.
Set the input coupling to AC.
Set the signal ground to FLOAT.
Set the line filter to THRU.
Use INT OSC (internal oscillator) as the reference signal source.
Set the amplitude to 1 V (rms).
Set the sensitivity to 200 μV (rms) and the DR setting to LOW.
Set the time constant to 100 ms.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Set measurement parameter DATA1 to R.
Frequency is per the following table.
: Only BNC cable and divider.

Measurement
instrument settings
Connections

Measurement method
Judgment (Pass Range): Connect a BNC cable from one side of a divider at the LI 56xx OSC
OUT connector to connector A. Connect a BNC cable from the otherside of the divider to connector B.
: At the frequencies in the following table, read the displayed DATA1
value.
: Per the following table.

Divider

BNC Cable

Two short BNC cables with thesame characteristics

Judgment
Frequency Range

Time Constant

DATA1 (rms)

55 Hz

200 ms.

μV< 10 μV

1 kHz

100 ms.

μV< 10 μV

8-20

Pass Range

LI 5655 / LI 5660

8.6 Performance Test

8.6.7 Input referred noise.
LI 56xx settings

Measurement
instrument settings
Connections
Measurement method

Judgment (Pass Range)

SHORT
PLUG

: Use connector A for signal input.
Set the input coupling to AC.
Set the signal ground to FLOAT.
Use INT OSC (internal oscillator) as the reference signal source.
Set the amplitude to 0V (rms).
Set measurement parameter DATA1 to NOISE.
Set sensitivity to 200 nV/ Hz and DR to LOW.
Set the time constant to 100 ms.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Frequency is per the following table.
: Shorted plug
(if necessary, use an oscilloscope): Connect a shorted plug to connector A.
: Read the displayed DATA1 value.
(Note: If large fluctuations make reading difficult, connect an
oscilloscope to LI 56xx DATA OUT1. Set the time axis to 10 s/div ormore and read the center value of the noise amplitude.): Per the following table.

Oscilloscope

Judgment
NOISE

Pass Criteria*2_ . _ nV/ Hz

4.5 nV/ Hz*2. Supplementary value. Not guaranteed. Frequency 1 kHz.

8-21

LI 5655 / LI 5660

8.6 Performance Test

8.6.8 Phase Accuracy
1) Versus an external reference signal
LI 56xx settings

Measurement instrument
settings
Connections

Measurement method
Judgment (Pass Range): Use connector A for signal input.
Set the input coupling to DC.
Set the signal ground to FLOAT.
Use REF IN (external reference signal) for the reference signal source.
Select the SIN+ reference signal waveform.
Set the sensitivity to 1 V (rms) and DR setting to LOW.
Set the attenuation slope to 24 dB/oct (SYNC OFF).
Set measurement parameter DATA2 to θ.
Frequencies and time constants are as in the following table.
: Set the generator to sine wave.
: Connect a BNC cable from one side of a divider at the generator output
connector to connector A. Connect a BNC cable from the other side ofthe divider to the REF IN connector.
: Set the following frequencies and time constants and read the displayed
DATA2 value.
: Per the following table.

Generator
1.00000 kHz
1.000 Vrms
FUNC OUT SYNC OUTBNC Cable (1 m)

Divider

BNC Cable (1 m)* Two short, equal-length BNC cables with the same characteristics.

8-22

LI 5655 / LI 5660

8.6 Performance Test

Judgment
Frequency
10 Hz
1 kHz
10 kHz
100 kHz
1 MHz
3 MHz

Time Constant
1s
100 ms
10 ms
10 ms
10 ms
10 ms

θ
___.__°___.__°___.__°___.__°___.__°___.__°

Pass Criteria*2-1 to +1 °-1 to +1 °-1 to +1 °-2 to +2 °-5 to +5 °-10 to +10 °*2. Supplementary value. Not guaranteed.
Check that that the value is roughly within this range.
If too far off, there may be damage.
2) Versus the internal oscillator
LI 56xx settings: Change the following "1) Versus an external reference signal "settings.
Use INT OSC (internal oscillator) as the reference signal source.
Set the amplitude to 1 Vrms.
: Only BNC cable.

Measurement
instrument settings
Connections
Measurement method
Judgment (Pass Range): Connect a BNC cable from the LI 56xx OSC OUT connector toconnector A.
: Set the following frequencies and time constants and read thedisplayed DATA2 value.
: Per the following table.

BNC Cable (1 m)

Judgment (same as " Versus an external reference signal ")Frequency
10 Hz
1 kHz
10 kHz
100 kHz
1 MHz
3 MHz

Time Constant
1s
10 ms
10 ms
10 ms
10 ms
10 ms

θ
___.__°___.__°___.__°___.__°___.__°___.__°

Pass Criteria*3-1 to +1 °-1 to +1 °-1 to +1 °-2 to +2 °-5 to +5 °-10 to +10 °*3. Supplementary value. Not guaranteed.

8-23

LI 5655 / LI 5660

8.6 Performance Test

8.6.9 Frequency Accuracy
LI 56xx settings

Measurement
instrument settings
Connections
Measurement method
Judgment (Pass Range): Use INT OSC (internal oscillator) as the reference signal source.
Set the frequency to 1 kHz and amplitude to 1 V (rms).
Open 10 MHz IN (external synchronous 10 MHz).
Signal input connectors, input coupling, signal ground, measurement
parameters, sensitivity, DR setting, time constant and attenuation slope
can be set arbitrarily.
: Use a frequency counter: Connect the LI 56xx OSC OUT connector to the frequency counter
with a BNC cable.
: Read the measured value on the frequency counter.
: Per the following table.

Frequency Counter
1.000009kHz

BNC Cable (1 m)

Judgment
Measured value_ . _ _ _ _ _ _ kHz

Pass Range
0.999960 to 1.000040 kHz

8-24

LI 5655 / LI 5660

8.6 Performance Test

8.6.10 Amplitude Accuracy of Internal Oscillator Sine Wave Output
LI 56xx settings

Measurement
instrument settings
Connections
Measurement method
Judgment (Pass Range): Use INT OSC (internal oscillator) as the reference signal source.
Signal input connectors, input coupling, signal ground, measurement
parameters, sensitivity, DR setting, time constant and attenuation slope
can be set arbitrarily.
Frequency, amplitude and amplitude range are per the following table.
: Set the DMM for 1 kHz in AC voltage mode.
For 100 kHz to 3 MHz, use the RMS Voltmeter.
: Connect the LI 56xx OSC OUT connector to the DMM (or RMS
Voltmeter) with a BNC cable.
: Read the measurement values on the DMM (or RMS Voltmeter).
: Per the following table.

DMM
or RMS Voltmeter
BNC Cable (1 m)
0.9999 V AC

BNC-Banana
Conversion
Adapter

Judgment
Amplitude
Range
(rms)

Amplitude
Setting
(rms)

1V

1V

1V

100 mV

100 mV

100 mV

10 mV

10 mV

1 kHz
0.979 to 1.021_ .___ _V
97.0 to 103.0_ _ _ . _ _ mV
97.0 to 103.0_ _ _ . _ _ mV
8.80 to 11.20_ _ . _ _ _ mV

8-25

Pass Range
Voltmeter Reading (rms)
1 MHz
0.958 to 1.042_ . _ _ _ _V
94.0 to 106.0_ _ _ . _ _ mV
94.0 to 106.0_ _ _ . _ _ mV
4.30 to 12.40_ _ . _ _ _ mV

3 MHz
0.925 to 1.075_ . _ _ _ _V
88.0 to 112.0_ _ _ . _ _ mV
88.0 to 112.0_ _ _ . _ _ mV
4.30 to 15.70_ _ . _ _ _ mV

LI 5655 / LI 5660

8.6 Performance Test

8.6.11 AUX IN DC Voltage Measurement Accuracy
LI 56xx settings

Measurement instrument
settings
Connections

Measurement method

Judgment (Pass Range): Set measurement parameter DATA1 to AUX1, and DATA2 to AUX2.
Reference signal source, frequency, amplitude, signal input connectors,
input coupling, signal ground, sensitivity, DR setting, time constant andattenuation slope can be set arbitrarily.
Set AUX OUT1 per following table.
: Set the DMM to DC voltage mode.
: Connect a BNC cable from one side of a divider at the LI 56xx AUX
OUT1 connector to AUX IN1 (or AUX IN2). Connect a BNC cablefrom the other side of the divider to the DMM.
: Read the measured value of the output voltage at AUX OUT1 on the
DMM, and the displayed value of DATA1 (or DATA2).
Also read the value when the shorting plug is connected to AUX IN1(or AUX IN2)
: Per the following table.

SHORT
PLUG

DMM
9.9999 V DC

BNC-Banana
Conversion Adapter

BNC Cable

Judgment
AUX OUT 1

DMM reading: M

Measured value
AUX IN 1
AUX IN 2

Pass Range.

M×0.997－0.01：+
+10 V

+

.

V

to
－10 mV to +10 mV

-

.

V

to
M×1.003-0.01：-

8-26

V

＋

.

V

.

.

mV

mV

.

M×0.997＋0.01：-10 V.

.

M×1.003＋0.01：+(short-circuited
input)

＋

－

.

V

－

.

V

.

LI 5655 / LI 5660

8.6 Performance Test

8.6.12 AUX OUT RMS Voltage Accuracy
LI 56xx settings

Measurement
instrument settings
Connections
Measurement method
Judgment (Pass Range): Measurement parameters, reference signal source, frequency,
amplitude, signal input connectors, input coupling, signal ground,sensitivity, DR setting, time constant and attenuation slope can be set
arbitrarily.
Set AUX OUT1 and AUX OUT2 per following table.
: Set the DMM to DC voltage mode.
: Connect the LI 56xx AUX OUT1 (or AUX OUT2) connector to the
DMM with a BNC cable.
: Read the measured value of the output voltage at AUX OUT1 (or AUX
OUT2) on the DMM.
: Per the following table.

DMM
BNC Cable
9.9999 V DC

BNC-Banana
Conversion Adapter

Judgment
AUX OUT 1, 2
Voltage Setting
+10 V
0V
-10 V

Pass Range
DMM reading
AUX OUT 1+9.96 to +10.04+.
V-10 to +10.
mV-10.04 to -9.96
.
V

8-27

AUX OUT 2+9.96 to +10.04+.
V-10 to +10.
mV-10.04 to -9.96.
V

LI 5655 / LI 5660

8.7 Calibration

8.7 Calibration
If the performance test results do not satisfy the specifications, NF Corporation will perform adjustment orcalibration to restore the original performance.
If calibration is required, contact NF Corporation or one of our agents.
After warranty expiration, we provide adjustment and calibration for a fee.

8-28

LI 5655 / LI 5660

8.8 Maintenance Information

8.8 Maintenance Information
The {Maintenance Information Screen} shown below is for maintenance tasks such as repairs andcalibration. It is not applicable to user operations.
To view the {Maintenance Information Screen}, press the ＿UTIL＿ key to display to the Utility Screen.
Pressing the [SYSTEM>] soft key switches to the {System
Setting Screen}.
Pressing

the[SERVICE>]

soft

key

displaysthe{Maintenance Information Screen}.

＿UTIL＿ key(Operation Screen Selection Keys){Maintenance Information Screen}

Running Time (min.)Number of Starts

Not disclosed(times)8-29

LI 5655 / LI 5660

8.8 Maintenance Information(Blank)8-30

LI 5655 / LI 5660

9． Specification

9.1 Measured signal system ....................................................... 9-2
9.2 Phase Sensitive Detector Section......................................... 9-7
9.3 Reference Signal System.................................................... 9-11
9.4 Arithmetic Processing ......................................................... 9-15
9.5 Measured Value Output and Display Section .....................9-17
9.6 Monitor Output.....................................................................9-18
9.7 Auxiliary Input (DC Voltage Measurement)......................... 9-19
9.8 Auxiliary Output (DC Voltage Output) .................................9-19
9.9 Automatic Setting Items ......................................................9-19
9.10 Data Memory ......................................................................9-20
9.11 Remote Control Interface ...................................................9-21
9.12 General Specifications .......................................................9-22
9.13 External Dimensions Diagram............................................9-23

Nominal, Typical, Supplement and Approximate values
These values show the supplemental data of this product and do notguarantee the performance.

9-1

LI 5655 / LI 5660

9.1 Measured signal system

9.1 Measured signal system*1. The C and HF connectors are present only on the LI 5660, and not on the LI 5655.
Therefore, specifications regarding C and HF connectors apply only to the LI 5660.
a) Voltage Measurement
Input connector

BNC (Front panel A, B, C,*1 HF*1)
Use B for A-B (differential input).

Input type

A, C*1, HF*1

single-end,

A-Bdifferential

Frequency range
A, A-B, C*1
HF*1

0.5 Hz to 3 MHz
10 kHz to 11 MHz

Sensitivity
A, A-B

10 nV to 1 V f.s. (1-2-5 sequence)

1C*

1 mV to 10 V f.s. (1-2-5 sequence)

HF*1

1 mV to 1 V f.s. (1-2-5 sequence)

 1-2-5 sequence in repeating progression
1, 2, 5, 10, 20, 50, 100, 200, 500, ...
Voltage accuracy
A, A-B±0.5 % (1 kHz, signal level ≧ 1 mV, 23 ±5 °C)*2±2 % (1 kHz, signal level ≧ 1 μV)*2±0.5 % (≦20 kHz, sensitivity 100 mV to 1 V at 23 ±5 °C)*3±1 % (≦50 kHz, sensitivity 100 mV to 1 V )*3±2 % (≦100 kHz, sensitivity 100 mV to 1 V )*3±3 % (≦1 MHz, sensitivity 100 mV to 1 V )*3±5 % (≦3 MHz, sensitivity 100 mV to 1 V )*3*2. with at least 30% full-scale signal (sensitivity), and dynamic reserve LOW*3. with DC coupling, dynamic reserve LOW , and full-scale signal
For details about dynamic reserve,

 "9.2 Phase Sensitive Detector c) Dynamic Reserve (DR)"C*1±0.5 % (≦20 kHz)
±1 % (≦50 kHz)
±2 % (≦100 kHz)
±3 % (≦1 MHz)
±5 % (≦3 MHz)
with sensitivity 1 V to 10 V, full-scale signal, and dynamic reserve LOW

9-2

LI 5655 / LI 5660

9.1 Measured signal system

HF*1±3 % (≦1 MHz, input impedance 1 MΩ)±5 % (≦3 MHz, input impedance 1 MΩ)±7 % (≦10 MHz, input impedance 50 Ω)±14 % (≦11 MHz, input impedance 50 Ω)
dynamic reserve LOW, sensitivity 100 mV to 1 V, and full-scale signal

Voltage accuracy temperature drift
A，A-B± 100ppm / °C (supplementary value)
f: 1 kHz, dynamic reserve LOW, A input, sensitivity 1V, signal level 100 % of
full-scale sensitivity

Input impedance
A，B

10 MΩ (nominal value), 50 pF in parallel (supplementary value)1

1 MΩ (nominal value), 50 pF in parallel (supplementary value)*1

1 MΩ (nominal value), 50 pF in parallel (supplementary value)C*

HF｜50 Ω (nominal value)
Input referred noise.
A，A-B

4.5 nV/√Hz (supplementary value)

dynamic reserve LOW, sensitivity 1 mV or less, frequency 1 kHz, input shortCommon-mode rejection ratio
A-B

at least 100dB
AC coupling, 50 Hz to 1 kHz, signal source impedance 0 Ω, dynamic reserve
LOW, and sensitivity 20 mV or less (or MED and 2 mV or less)Harmonic distortion
A，A-B−80 dBc or less (10 Hz to 5 kHz, 2-3rd order harmonics, each order)
dynamic reserve LOW, sensitivity 1 V, signal level 30 % of full-scale sensitivity.

Maximum input voltage (linear operating range)
A，B，A-B± 3 V (each connector voltage and differential voltage at DC coupling)
dynamic reserve HIGH, sensitivity 1 V*1± 30 Vdynamic reserve HIGH, sensitivity 10 V

HF *1

±3V
dynamic reserve HIGH, sensitivity 1 V

C

9-3

LI 5655 / LI 5660

9.1 Measured signal system

Nondestructive maximum input voltage
A, B

AC coupling: 10 Vrms, sine wave, ±42 V DC
DC coupling: ±14 V
When a signal is over-range, the internal signal protection circuit temporarily
disconnects the input connector.

1

C*

±42 V

HF*1

±5 V

b) Current measurement
Input connector

BNC (front panel I)

Input type

Single-end

Frequency range

0.5 Hz to maximum values shown in the table below (nominal values, 3dB
reduction frequency)
Conversion Gain
1 M (106) [V/A]
100 M (108) [V/A]
1 MHz
10 kHz
1 MHz
10 kHz150 kHz
1.5 kHz

Cs*4
None
150 pF
1 nF*4. Signal Source + Connection Cable CapacitanceSensitivity

100 fA to 1 μA f.s. (with 1 M V/A conversion gain)
10 fA to 10 nA f.s. (with 100 M V/A conversion gain)
Both in 1-2-5 sequence

Current accuracy±1 %at 23 ±5 °C, dynamic reserve LOW,
sensitivity 1 μA (1 M V/A conversion gain at 1 kHz) as well as
sensitivity 10 nA (100 M V/A conversion gain at 125 Hz),
30% or more of full-scale sensitivity signal
Both are typical values

Current accuracy temperature drift± 150 ppm / ℃
dynamic reserve LOW, supplementary value for (conversion gain 1 M [V/A],
1 kHz) and (conversion gain 100 M [V/A], 125Hz)
Input referred noise150 fA/ Hz (1 M V/A conversion gain at 1 kHz)
15 fA/ Hz (100 M V/A conversion gain at 125 Hz)

Input impedance

Both are supplementary values
1 kΩ (1 M V/A conversion gain)
100 kΩ (100 M V/A conversion gain)
Both are supplemantary values

9-4

LI 5655 / LI 5660

9.1 Measured signal system

Maximum input current (linear operating range)±3 μA
With DC coupling, dynamic reserve HIGH, conversion gain 1 M [V/A] ,sensitivity 1 μA
Non-destructive maximum input current±10 mAc) Noise density measurement
Sensitivity

Voltage

20 nV/ Hz to 1 V/ Hz (at inputs A, A-B)
1 mV/ Hz to 10 V/ Hz (at input C *1)
1 mV/ Hz to 1 V/ Hz (at HF input *1)

Current

1 pA/ Hz to 1 μA/ Hz (with 1 M V/A at input I)
100 fA/ Hz to 10 nA/ Hz (with 100 M V/A at input I)
All in 1-2-5 sequenced) Input Coupling*1

A, A-B:

AC/DC switching
AC coupling with two-stage cascaded 1st order HPF
HPF fc: 0.1Hz (nominal value),I:

AC/DC switching, After converting the voltage

C*1:
*1

HF :

DC (Always automatically cancel DC component)
ACfc: 1 kHz (nominal value),when input impedance is 50Ω, the AC-couple stage is positioned
after the 50Ω termination one.

e) Input Ground

FLOAT / CONNECT (to chassis)
Withstand voltage

switching: ± 1 Vpk max. (DC+AC)

Impedance to chassis (nominal value): 10 kΩ (float), 11 Ω (connected to the chassis)
Remarks: The outer contacts of input connectors A, B, C*1, HF*1, I and the preamp power supply
output (PREAMP POWER) ground line (0 V) are connected together internally.
Other input and output signal grounds that are not specified otherwise are connected to thechassis.

9-5

LI 5655 / LI 5660

9.1 Measured signal systemf) Line Filter

rejection frequency (fundamental)
50 Hz | 60 Hz

selectFunction

ThroughFundamental rejection( 50 Hz or 60 Hz)



2 nd order harmonics rejection(100 Hz or 120 Hz)Both of Fundamental and 2 nd order harmonics rejection

Attention
20 dB or more (at f0)
Restrictions
When using the input C*1 and HF*1, Line filter is disable regardless ofLine filter settings.

9-6

LI 5655 / LI 5660

9.2 Phase Sensitive Detector Section

9.2 Phase Sensitive Detector Section*1. The C and HF connectors are present only on the LI 5660, and not on the LI 5655.
Therefore, specifications regarding C and HF connectors apply only to the LI 5660.
a) Phase Sensitive Detector (PSD)
2 phase (Rcos θ, Rsin θ), Dual PSD (primary PSD, secondary PSD).
Settings Items

Primary PSD

Secondary PSD

Individual*2
Individual
Individual
Individual
Common with
Dynamic Reserve
IndividualPrimary PSD*2. The sensitivity of the secondary PSD is limited by that of the primary PSD.
Sensitivity
Time ConstantPhase
XY Offset

Individual
Individual
Individual
Individual

The sensitivity setting of the secondary PSD can be higher than that of the
primary PSD, but cannot be lower. (For example, if primary PSD sensitivity
is 1 mV, secondary PSD sensitivity can be set to 500 μV, but not 2 mV.)b) Detection Modes
Measurement Frequency
primary PSD
secondary PSD

Detection ModeSINGLE*3
DUAL1*4
DUAL2*5

fundamental / fractional harmonic
fundamental / fractional harmonic
frimary frequency

none
fundamental /harmonic
secondary frequency

CASCADE*6

primary frequency

secondary frequency*3. 2-phase detection is at one frequency.
*4. The fundamental and a harmonic component of one input signal are measured simultaneously.
*5. Two independent frequency components (primary and secondary) of one input signal aremeasured simultaneously.
*6. The Secondary PSD is connected in cascade with the primary PSD, so after a signal isdetected by the Primary PSD, it is further detected by the secondary PSD.

For details about the primary and secondary frequencies,

"9.3 Reference Signal System" c) Internal Oscillators".

9-7

LI 5655 / LI 5660

9.2 Phase Sensitive Detector Sectionc) Dynamic Reserve (DR)
Effective Range

100 dB or more (supplementary value)

Settings

LOW / MEDIUM / HIGH 3-point switching

The actual value changes according to sensitivity and dynamic reserve settings, frequency difference
between signals and noise, and time constant filter setting. The following table shows nominal
values at frequencies for which noise is sufficiently attenuated by the time constant filter. Settings
that exceed 100 dB require a large time constant, and drift and measurement value errors may
become larger.
 dynamic reserve (DR) definition
DR = Maximum acceptable noise level ÷ Sensitivity (full-scale signal)
Inputs: A, A-B, I
DR Setting
Sensitivity (each input)
I (1M)I (100M)

A，A-B

1 μA
500 nA
200 nA
100 nA
50 nA
20 nA
10 nA
5 nA
2 nA
1 nA
500 pA
200 pA
100 pA
50 pA
20 pA
10 pA
5 pA
2 pA
1 pA
500 fA
200 fA
100 fA-------

10 nA
5 nA
2 nA
1 nA
500 pA
200 pA
100 pA
50 pA
20 pA
10 pA
5 pA
2 pA
1 pA
500 fA
200 fA
100 fA
50 fA
20 fA
10 fA
-------------

1V
500 mV
200 mV
100 mV
50 mV
20 mV
10 mV
5 mV
2 mV
1 mV
500 μV
200 μV
100 μV
50 μV
20 μV
10 μV
5 μV
2 μV
1 μV
500 nV
200 nV
100 nV
50 nV
20 nV
10 nV

LOW
AC
DR
Gain
dB
dB
0
6
6
6
14
6
20
6
26
6
34
6
40
6
42
10
48
12
54
12
56
16
56
24
56
30
56
36
56
44
56
50
56
56
56
64
56
70
56
76
56
84
56
90
56
96
104
56
110
56

MEDIUM
AC
DR
Gain
dB
dB
0
6
0
12
6
14
12
14
14
18
20
20
26
20
32
20
32
28
32
34
32
40
32
48
32
54
32
60
32
68
32
74
32
80
32
88
32
94
32
100
108
32
114
32
120
32
128
32
134
32

HIGH
AC
DR
Gain
dB
dB
0
6
0
12
0
20
0
26
0
32
0
40
0
46
0
52
0
60
0
66
0
72
0
80
0
86
0
92
0
100
106
0
112
0
120
0
126
0
132
0
140
0
146
0
152
0
160
0
166
0

AC Gain: Gain ahead of the phase sensitive detector (PSD)(common to primary and secondary PSDs)
Gain dB = 20 × log10 (linear gain) dB
Example: 10 times → 20 × log10 10 = 20 dB

9-8

LI 5655 / LI 5660

9.2 Phase Sensitive Detector Section

Input: C*1
DR Setting
Sensitivity(Input C)
10 V
5V
2V
1V
500 mV
200 mV
100 mV
50 mV
20 mV
10 mV
5 mV
2 mV
1 mV

LOW
AC
DR
Gain
dB
dB
0
6
6
6
14
6
14
12
14
18
14
26
14
32
14
38
14
46
14
52
14
58
14
66
14
72

MEDIUM
AC
DR
Gain
dB
dB
0
6
0
12
6
14
6
20
6
26
6
34
6
40
6
46
6
54
6
60
6
66
6
74
6
80

HIGH
AC
DR
Gain
dB
dB
0
6
0
12
0
20
0
26
0
32
0
40
0
46
0
52
0
60
0
66
0
72
0
80
0
86

LOW
AC
DR
Gain
dB
dB
0
6
6
6
14
6
20
6
20
12
20
20
20
26
20
32
20
40
20
46

MEDIUM
AC
DR
Gain
dB
dB
0
6
0
12
6
14
6
20
6
26
6
34
6
40
6
46
6
54
6
60

HIGH
AC
DR
Gain
dB
dB
0
6
0
12
0
20
0
26
0
32
0
40
0
46
0
52
0
60
0
66

Input: HF*1
DR Setting
Sensitivity(Input HF)
1V
500 mV
200 mV
100 mV
50 mV
20 mV
10 mV
5 mV
2 mV
1 mV

Secondary PSD dynamic reserve includes the sensitivity ratio of the primary PSD'sdynamic reserve.
secondary PSD DR＝primary PSD DR＋20×log10 (primary PSD sensitivity ÷ secondary
PSD sensitivity) dB
Ex.) Input A, DR set to HIGH, primary PSD sensitivity 2 mV (DR value: 60 dB),
When secondary PSD sensitivity is 1 mV
secondary PSD DR ＝ 60 dB＋20×log10 (2 mV÷1 mV) dB ＝ 66 dB

9-9

LI 5655 / LI 5660

9.2 Phase Sensitive Detector Sectiond) Time Constant Filter
Time constant

1 μs to 50 ks (1-2-5 sequence)

Attenuation slope

6, 12, 18, 24 dB/oct

Synchronous filter

on/off About the Time Constant Filter
A cascaded first-order low-pass filter suppresses noise and ripple associated with phase sensitive
detection.
This digital low-pass filter exhibits the same exponential response as an analog filter.
The time constant setting determines the response time of the first-order low-pass filter, and theattenuator slope is determined by the filter cascade (6 dB/oct per step).
The higher each setting, the greater the noise and ripple rejection ratio.
The following types of synchronous filter are available.
 About the Synchronous Filter
This is an integer-period moving-average filter.
Ripple caused by detection is greatly reduced, and the output is nearly settled in the averaging
interval (integer period), so the time constant can be reduced (to obtain faster response).
However, at higher signal frequencies, ripple suppression may be insufficient.
e) Others
Phase noise

0.001 ° rms (at 1 kHz, 18 dB/oct or greater attenuation slope)0.003 ° rms (at 100 kHz, 12 dB/oct or greater attenuation slope)0.01 ° rms (at 3 MHz, 12 dB/oct or greater attenuation slope)
Supplementary value; reference signal is external sine wave 1Vrms, time
constant 100ms, synchronization filter off

Phase temperature drift ±0.01 °/°C (from 100 Hz to 10 kHz)

±0.03 °/°C (from 10 kHz to 100 kHz)
±0.2 °/°C (from 100 kHz to 3 MHz)
Supplementary value when input signal (A connector) and external reference
signal (REF IN connector) are both Sine wave 1Vrms.

9-10

LI 5655 / LI 5660

9.3 Reference Signal System

9.3 Reference Signal System*1. The C and HF connections are present only on the LI 5660, and not on the LI 5655.
Therefore, specifications regarding C and HF connectors apply only to the LI 5660.
a) Reference signal source
REN ININT OSC
SIGNAL

external reference signal*2
interenal oscillator
measured signal*3

In SIGNAL, the reference signal is so synchronized with an input signal that thephase measurement value becomes zero.
*2 : The external reference signal is used as the primary PSD’s reference
frequency at SINGLE, DUAL1, and DUAL2, and is used as the secondary
one at CASCADE.
*3 : This mode cannot be used when input HF is selected.
b) External reference signal
Waveform
SIN POSThe waveform crosses the threshold level only twice per period.
The negative to positive crossing of the mean value isestablished as 0°.
TTL POSThe square wave crosses the threshold level only twice perperiod.
The rising edge is 0°.
TTL NEGThe square wave crosses the threshold level only twice perperiod.
The falling edge is 0°.
Input connector
BNC (front panel REF IN)
Input impedance
1 MΩ (nominal value), 100 pF in parallel (supplementary value)
Input voltage range
SIN
0.3 to 20 Vp-p (sine wave)
TTL
0 to 5 V, High 2.6 V or more, Low 0.8 V or less (square wave)
Pulse width (square wave)
40 ns or more (both high and low levels)
Nondestructive maximum input voltage±15 V
Synchronization frequency range
per following table
SignalInput

Detection
Mode

A
A-B
C *1
I

SINGLE
DUAL1
DUAL2
CASCADESINGLE
DUAL1
DUAL2

HF *1

CASCADE

9-11

External
Reference Signal
Waveform

Synchronous
Frequency Range

SIN POSTTL POSTTL NEG

0.3 Hz to 3.2 MHz

TTL POSTTL NEG

8 kHz to 11.5 MHz

SIN POSTTL POSTTL NEG

0.3 Hz to 3.2 MHz

LI 5655 / LI 5660

9.3 Reference Signal System

Synchronization time 2 periods + 50 ms (supplementary value)
Frequency display resolution
6 digits (to 0.1 mHz below 100 Hz)
Frequency measurement accuracy±(40 ppm + 1 count)c) Internal Oscillator*1
Frequency (primary and secondary)setting range

0.3 Hz to 11.5 MHz
For A, A-B, C*1, and I inputs, 0.3 Hz to 3.2 MHz
with HF*1 input, 8 kHz to 11.5 MHz

Resolution

6 digits (to 0.1 mHz below 100 Hz)
Accuracy±40 ppm

For numerical value settings, frequency is stable immediately after setting.
 About primary and secondary frequencies
Two distinct frequencies are generated for DUAL2 and CASCADE detection modes. The primary
frequency is that of the internal oscillator connected to the primary PSD. The secondary frequency isthat of the internal oscillator connected to the secondary PSD.

Reference frequency source
Internal/external switching (external 10 MHz sync function)
External reference frequency
Input connector

BNC (Rear panel 10MHz IN)

Frequency range

10 MHz ±0.2%

Waveform

Sine or square wave (45 to 55% duty cycle)

Signal level

0.5 Vp-p to 5 Vp-p

Non-destructive maximum input voltage
10 Vp-pInput impedance

1 kΩ (nominal value)

Input couplingAC

Withstand voltage (Allowed voltage to ground)±42 Vpeak max (DC+AC) About the External 10 MHz syncronization Function
This 10 MHz reference frequency for frequency synthesis is provided from an external oscillator,and can be used to synchronize with the reference frequency. Therefore, even if no externalreference signal (REF IN) is available, synchronization is available by numerical frequency settingof the internal oscillator.

9-12

LI 5655 / LI 5660

9.3 Reference Signal System

Sine wave output
Output connector

BNC (front panel OSC OUT)

Frequency

primary frequency (with detection mode SINGLE, DUAL1)
primary frequency or secondary frequency (With detection mode DUAL2,
CASCADE, can be selected)

Amplitude

Per following table
Range

10 mV
0 to
10.00 mVrms
0.01 mVrms

ExtentResolution

100 mV0 to
100.0 mVrms
0.1 mVrms

1V
0 to
1.000 Vrms
0.001 Vrms

Amplitude accuracy±(2 % of setting + 1 mV) ≦ 20 kHz±(3 % of setting + 1 mV）≦ 100 kHz±(4 % of setting + 2 mV）≦ 1 MHz±(7 % of setting + 5 mV）≦ 3 MHz
When > 3.2 MHz, 0 Vrms regardless of the setting.
Maximum output current±15 mA
Load: Resistor connected to signal ground. Following is the same.
Output impedance

50 Ω (nominal value)

Harmonic distortion -80 dBc or less (20 Hz to 5 kHz)*4-70 dBc or less (5 kHz to 100 kHz)*4-60 dBc or less (100 kHz to 1 MHz)*5-50 dBc or less (1 MHz to 3 MHz)*5
Output voltage setting 1Vrms*4 : No load, supplementary value for each of 2nd to 5th order harmonic*5 : 50 Ω load, supplementary value for each of 2nd and 3rd order harmonic
Square wave output
Output connector

BNC (rear panel REF OUT)

Frequency

Same as sine wave output

Signal level

TTL (0 to 3.3 V nominal /no load), ±8 mA max

Restrictions

Above 3.2 MHz and with 0 Vrms sine amplitude, output is unstable (fixed athigh or low level).

9-13

LI 5655 / LI 5660

9.3 Reference Signal Systemd) Harmonic measurement
detection mode SINGLE
The primary frequency to the PSD is n/m times of reference signal frequency.
n range (harmonic)

1 to 63m range (sub harmonic)

1 to 63detection mode DUAL1
The primary frequency to the primary PSD is n/m times of the reference signal frequecy. And
the secondary frequency to the secondary PSD is n times of the reference signal frequency.
n PRI range (harmonics number of primary PSD)

1 to 63m PRI range (sub harmonics number of primary PSD)

1 to 63n SEC range (harmonics number of secondary PSD)

1 to 63

Harmonics are measured under the following conditions.
Reference
Fundamental frequency range
Signal Source
Synchronization frequency range to
REF IN
external reference signal
Internal oscillator frequency setting
INT OSC
range
Synchronization frequency range to
SIGNAL
external reference signal

Harmonic frequency range
Same as at left
Same as at left
Regardless of n, m settings,
always operates at n = 1 and m = 1e) Phase Adjustment
Phase shift amountRange-180.000° to +179.999°

Resolution

0.001°f) Others
Orthogonality±0.001° or better (supplementary value)

Phase accuracy±1° (DC coupling, ≦10 kHz)±2° (DC coupling, ≦ 100 kHz)±5° (DC coupling, ≦ 1 MHz)
±10° (DC coupling, ≦ 3 MHz)
Reference signal source = REF IN
Signal input connector A (sensitivity 1 V),
Supplementary value when input signal (A connector) and external reference
signal (REF IN connector) are both Sine wave 1Vrms.

9-14

LI 5655 / LI 5660

9.4 Arithmetic Processing

9.4 Arithmetic Processing
The following calculations are available for measurement values X, Y and R.
For measurement values X, Y and R,  "9.5 Measured Value Output and Display Section"a) Offset adjustment

Control

Enable/Disable

X, Y:sensitivity of ± 105% (resolution 0.001%)

Both of primary PSD and secondary PSD can be set About Offset Adjustment
This function enables deduction of a certain amount from the detectors' X and Y outputs. Use it tocancel crosstalk components contained in the input. Also, by setting X and Y near zero, thefollowing expansion capabilities can be used to improve the apparent sensitivity and resolution,
enabling measurement of small changes.
b) Expansion
EXPAND

X, R:

1, 10, 100 (Ratio of X and R is common)Y:

1, 10, 100

Primary PSD and secondary PSD can be set individual
Apparent sensitivity (signal F. S.) is 1 / EXPAND magnification
Unusable when normalize or ratio arithmetic processing is running.
c) Normalize

Select from the followingNone% value= (measured value / standard value) x 100

dB value= 20 × log10 | measurement values / standard values |% FS value= (measured value / sensitivity) × 100

When detection mode is SINGLE, DUAL1, DUAL2,
the above measurement value = primary PSD output (X or R)
When detection mode is CASCADE,
the above measurement value = secondary PSD output (X or R)
Standard value range: voltage 1nV to 10V: current 1fA to 1μA: resolution 6-digit
Unusable when EXPAND or Ratio arithmetic processing is running.

9-15

LI 5655 / LI 5660

9.4 Arithmetic Processingd) Ratio

Select from the following


None



ratio = K × A ÷ B

K:range 0.1 to 10 (resolution 0.00001)

A, B:
Select from a combination of the below
A (measured value)
B (standard value)
primary PSD output(X, Y, R) / sensitivity

AUX IN 1
measured value / 10 V

primary PSD output
secondary PSD(X, Y, R) / sensitivity
X output / sensitivity
secondary PSD output
AUX IN 1(X, Y, R) / sensitivity
measured value / 10 V
Maximum update rate of B is about 10 k samples/s.

detection mode
SINGLE
DUAL1
DUAL2
DUAL1
DUAL2
CASCADE

When executing expansion or normalizing or ratio arithmetic procesing cannot
be performed.
 About the Ratio
This is the ratio of measured value A to standard value B. Determining the ratio enables cancelingout characteristic variation of the parts common to the measurement and standard systems (signal
source, path and sensor).
For a usage example,  "1.2 Applications" ■Application Examples Taking Advantage of
the Feature of the LI 5655 / LI 5660b) Measurement of Light Transmission and Absorption, andSuppression of illuminant Fluctuation

9-16

LI 5655 / LI 5660

9.5 Measured Value Output and Display Section

9.5 Measured Value Output and Display Sectiona) Parameter
Select from the following.
Output/Display

Detection Mode
DUAL1 DUAL2, CASCADE

SINGLE

DATA1
DATA2
DATA3
DATA4

X, R, AUX IN 1, NOISE

Xp,Rp,Yp, θp ,Xs, Rs,AUX IN 1, NOISE

Y, θ, AUX IN 1, AUX IN 2
X, R

Yp,θp,Xs,Rs, Ys,θs,AUX IN 1, AUX IN 2

Y, θRemarks:
X, Y, R, θsuffixn: Harmonic(At harmonic value settings, n
as a suffix. Ex.: Xn)

Yp,θp,Xs,Rs, Ys,θs
p: primary PSD
s: secondary PSD
n: Harmonic (At harmonic value settings, n as a suffix.
Ex.: Xpn)

Xp,Rp,Yp, θp ,Xs, Rs

X

In-phase component (=R cos θ)YQuadrature component (=R sin θ)R

Signal amplitude

θ

Signal phase

NOISE

Noise density (primary PSD only)

AUX IN 1

DC voltage (rear panel AUX IN 1)

AUX IN 2

DC voltage (rear panel AUX IN 2)b) Analog output
Front Panel
Output connectors

BNC (DATA OUT 1, DATA OUT2: corresponding to DATA1 and 2)

Maximum update rate

312.5 k samples/s.

Rear Panel
Output connectors

BNC (DATA OUT 3, DATA OUT4: corresponding to DATA3 and 4)

Maximum update rate

1.5625 M samples/s.

Common Specifications
Full-scale voltage±10 V (bipolar signals), +10 V (unipolar signals)

Output voltage range
Max output current±12 V (no-load)±10 mA

Output impedance

470 Ω (nominal value)

Output voltage accuracy±(0.3 % + 10 mV), versus measured value corresponding voltage
Refer to the rightmost column of the table in part "e) Numericaldisplay" for measured values corresponding voltage values.

9-17

LI 5655 / LI 5660

9.6 Monitor Outputc) Measurement screen display
Select the screen to display measurement values from the following.
Normal : show the measured values (DATA1, DATA2) and key settings
Large: enlarged display the measured values (DATA1, DATA2)

Fine: show the measured values (DATA1, DATA2, DATA3, DATA4) and advanced settingsd) Bar Graphs
On Normal and Large measurement screens, displays measured values as bar graphs as well as
numerical values.
e) Numeric display
Numeric display
Parameter

X, Y
R
θ
NOISE
(Noise dencity)
AUX IN 1，2
RatiosNormalize %Normalize% of f.s.
Normalize dB

Range

Resolution

Sensivity / Expand(±120%)
Sensitivity/EXPAND(0 to 120%)-180.000
to +179.999°
Sensitivity
0 to 120%± 12 V± 2.4± 240 %± 120 % of FS± 120 dB

6 digits,
at full-scale sensitivity
6 digits,
at full-scale sensitivity
0.001°
6 digits,
at full-scale sensitivity
0.0001 V
0.00001
0.001 %
0.001 % of FS
0.001 dB

Measurement value
for the full scale
voltage of theanalog output±Sensitivity/EXPAND
Sensitivity/EXPAND± 180 °
Sensitivity± 10 V±2± 200 %
± 100 % of FS± 100 dB

9.6 Monitor Output
Monitor signal

Phase sensitive detector input signal

Output connector

BNC (front panel MONITOR OUT)

Maximum output voltage±3 V (no-load)
Output is approximately AC Gain times the input.
For details of AC Gain, "9.2 Phase Phase Detection Section, c) Dynamic Reserve (DR)”Max output current±20 mA

Output impedance

50 Ω (nominal value)

9-18

LI 5655 / LI 5660

9.7 Auxiliary Input (DC Voltage Measurement)

9.7 Auxiliary Input (DC Voltage Measurement)
Number of channels

2

Input connectors

BNC (rear panel AUX IN 1, 2)

Maximum allowable input voltage (linear operating range)±12 V
Nondestructive maximum input voltage±42 V
1 MΩ (nominal value), 50 pF in parallel (supplementary value)

Input impedance

When signal ground is at chassis potential.
Voltage measurement accuracy± (0.3 % + 10 mV), when the input ground is equal to the chassis potential
Frequency bandwidth

Highest: 5 kHz (-3 dB) (supplementary value)

Sampling rate

Highest: 125 k samples/s

Floating characteristics

Signal Ground
Maximum voltage to ground (non-destructive)± 42Vpk max. (DC+AC)
Ground impedance
1MΩ (nominal value)
SignalMaximum voltage to ground (non-destructive)± 42Vpk max. (DC+AC)

9.8 Auxiliary Output (DC Voltage Output)
Number of channels

2

Output connectors

BNC (rear panel AUX OUT 1, 2)

Output voltage range±10.500 V (0.001 V resolution)

Maximum output current±5 mA
1 kΩ (nominal value)

Output impedance
Output voltage accuracy± (0.3% + 10 mV), no-load

9.9 Automatic Setting Items
Item
Measurement
Time constantSensitivity
Phase
OffsetFunction
Perform the following items "time constant", "sensitivity", "phase"
Set the time constant and attenuation slope corresponding to the frequency of thereference signal.
Set the sensitivity , and dynamic reserve according to the input signal.
Set the phase shift value as Y and phase output θ to a zero.
Set each offset value, X and Y outputs to a zero.

9-19

LI 5655 / LI 5660

9.10 Data Memory

9.10 Data Memory
Record data

For each sample data, select arbitrary up to five words from the following
recorded data
Recording data
Words
STATUS
1 WordDATA 1
1 WordDATA 2
1 WordDATA 3
1 WordDATA 4
1 WordReference Signal
2 Words
Frequency
STATUS detects the following signals.

Recording capacity
Trigger signal



UNLOCK (Unsynchronization)



PROTECT (Input A or B overload)



INPUT (pre PSD overload)

OUTPUT (post PSD overload)

AUX (AUX input overload)

Data Resolution
16 bits
16 bits
16 bits
16 bits
16 bits

Buffers 1, 2

16 to 8192 samples

Buffer 3

16 to 65536 sample (FIFO)

32 bits

Internal timer / External trigger / Remote control commands / Manual trigger
1 sample recorded when trigger signal is received

Sampling intervalInternal timer
Range: 1.92 µs to 20 s, repeated at equal intervals,

Resolution: 640ns, 6 digit max.

External trigger / Remote control commands / Manual trigger

External triggerRange: ≥ 2.6 μs arbitrary intervals,

trigger jitter: 640 ns (nominal value)

Input connector

BNC (rear panel TRIG IN)

Signal level

TTL (High 2.6 V or more, LOW 0.8 V or less)

Minimum pulse width

500 ns (both high and low level)

Effective edge

Falling

Input impedance

10kΩ (nominal value)

Nondestructive maximum input voltage±15 V
Trigger delay time

Range

0 to 100 s

Resolution

640 ns, 6 digits max

Data is recorded after the delay time has elapsed.
Operation

By remote control.
Can not operate from panel (only manual triggering is possible).

9-20

LI 5655 / LI 5660

9.11 Remote Control Interface

9.11 Remote Control Interface
USB

USBTMC, USB 2.0 HiSpeed

RS-232

Baud rate
4800, 9600, 19200, 38400, 57600, 115200, 230400 bps
Cable and controller characteristics can inhibit communication speeds over
19200 bps.
Flow control
None, Software (X-ON/X-OFF), Hardware (RTS/CTS)

GPIB

Compliance standards IEEE 488.1, IEEE 488.2

LAN

10BASE-T and 100BASE-TX, TCP/IP, LXI

9-21

LI 5655 / LI 5660

9.12 General Specifications

9.12 General Specifications
・Display

4.3-inch WQVGA, color LCD

・Power supply

AC 100 V ± 10 % / 120 V ± 10 % / 230 V+10 %, - 14 %However 250 V or less
50 Hz / 60 Hz ± 2 Hz, power consumption 75 VA or less
Overvoltage category Ⅱ• Environmental conditions
OperatingStorage

Temperature

0 to +40°C

Humidity

5 to 85% RH, absolute humidity 1 to 25 g/m3, non-condensing

Altitude2000 m or lessTemperature–10 to +50°C

Humidity

5 to 95% RH, absolute humidity 1 to 29 g/m3, non-condensing

Storage

Operating・Pollution degree
・Warm-up time・Setting memory
・Resume・Power output for preamp
・Key-Lock・Lamp control
・RoHS
・Safety and EMC

・External dimensions
・Weight

2 (indoor use)
30 miniutes
9 setsReturn to the last settings at power-on state± 15 V (nominal value)
100 mA max.(rear panel PREAMP POWER)
Present (On, Off)
Present (On, Off)
Remarks: Cooling fan is always on. It cannot be turned off.
Directive 2011/65/EU
EN 61010-1, EN 61010-2-030,
EN 61326-1, EN 61326-2-1
Remarks: Applies to products with CE marking displayedon the rear panel.
430(W) × 88(H) × 400(D) mm, excluding protrusions
Approx. 7.5 kg, except for accessories

9-22

LI 5655 / LI 5660

Top cover

9-23

Surface treatment
Front panel: Ultralight-gray plastic sheet (Munsell 6PB9.2/0.1 semi-gloss)
Rear panel: Light-gray coating (Munsell 6PB7.6/1.2 semi-gloss)
Cover: Light-gray leather-tone coating (Munsell 6PB7.6/1.2 leather tone)

Rear panel

9.13 External Dimensions Diagram

9.13 External Dimensions Diagram

Figure 9-1 LI 5655 External Dimensions Diagram

LI 5655 / LI 5660

Top cover

9-24

Surface treatment
Front panel: Ultralight-gray plastic sheet (Munsell 6PB9.2/0.1 semi-gloss)
Rear panel: Light-gray coating (Munsell 6PB7.6/1.2 semi-gloss)
Cover: Light-gray leather-tone coating (Munsell 6PB7.6/1.2 leather tone)

Rear panel

9.13 External Dimensions Diagram

Figure 9-2 LI 5660 External Dimensions Diagram

LI 5655 / LI 5660

9.13 External Dimensions Diagram

Figure 9-3 LI 5655 Panel Diagram

9-25

LI 5655 / LI 5660

9.13 External Dimensions Diagram

Figure 9-4 LI 5660 Panel Diagram

9-26

LI 5655 / LI 5660

ーーーー Warranty ーーーー
NF Corporation certifies that this product was thoroughly tested and inspected and found to meet its
published specifications when it was shipped from our factory.
All NF products are warranted against defects in materials and workmanship for a period of one year fromthe date of shipment. During the warranty period, NF will repair the defective product without any charge
for the parts and labor. For repair service under warranty, the product must be returned to either NF or an
agent designated by NF. Purchaser shall prepay shipping charge, duties and taxes for the product to either
NF or the agent from another country, and shipping charge for the return of the product to purchaser shallbe paid by NF side.
This warranty shall not apply to any defect, failure or damage caused by a) improper use; b) improper orinadequate maintenance and care; or c) modification by purchaser or personnel other than NF
representatives.

――― Request for Repair ―――
When a failure occurred and the product was found to be defective or you have any uncertainty, please getin touch with NF Corporation or one of our representatives.
In such a case, let us know the model name (or product name), serial number (SERIAL No. given on the
nameplate), and symptom and operating conditions as detail as possible.
Though we will make efforts to reduce the repair period, when five or more years have passed since youpurchased the product, it may take time due to, for instance, the out of stock of repair parts.
Also, if the production of repair parts is discontinued, the product is extremely damaged, or the product is
modified, we may decline the repair.

If there are any misplaced or missing pages, we will replace the manual.

Contact the sales

representative.
NOTES
 Reproduction of the contents of this manual is forbidden by applicable laws.
 The contents of this manual may be revised without notice.
 Information provided in this manual is intended to be accurate and reliable. However, we
assume no responsibility for any damage regarding the contents of this manual.
 We assume no responsibility for influences resulting from the operations in this manual.

LI 5655 / LI 5660 INSTRUCTION MANUAL (OPERATIONS)NF Corporation
3-20 Tsunashima Higashi 6-chome, Kohoku-ku. Yokohama-shi 223-8508, Japan
Phone +81-45-545-8111
Fax+81-45-545-8191

http://www.nfcorp.co.jp/◯
C Copyright 2016-2022, NF Corporation

http://www.nfcorp.co.jp/

NF Corporation
6-3-20, Tsunashima Higashi, Kohoku-ku, Yokohama 223-8508 JAPAN