SHF Communication Technologies AG
Wilhelm-von-Siemens-Str. 23D • 12277 Berlin • GermanyPhone +49 30 772051-0 • Fax +49 30 7531078
E-Mail: sales@shf.de • Web: http://www.shf.deDatasheet
SHF 78120 A
Synthesized Clock Generator

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Description
The Synthesized Clock Generator SHF 78120 A is designed to provide our BERT customers with astandalone compact clock source featuring a wide frequency coverage from 5 to 38 GHz, high output
power up to +8 dBm, low jitter and low harmonic levels. In combination with the SHF 12124 A Bit PatternGenerator and the SHF 11125 A Error Analyzer, it provides a compact and affordable high-speed testsolution.
The jitter injection functionality is integrated for jitter stress test applications. Arbitrary jitter types may
be applied to the clock signal using an external signal source, enabling various test scenarios such asserial data protocol compliance testing. An optional internal jitter source provides sinusoidal jitter from10 to 400 MHz with variable jitter amplitude.
An additional trigger output provides a trigger signal whose frequency can be switched to a quarter orhalf the output frequency. The trigger remains jitter-free even if jitter injection is used.

Block DiagramFeatures

Output clock frequency ranges from fCLK = 5 to 38 GHz with 1 MHz resolution



Output power adjustable from -10 to +8 dBm with 0.1 dB resolution

External jitter modulation

Supports three spread-spectrum clocking (SSC) modes10 MHz reference input and output for phase locking to other instrumentsRemote programming interface for automated measurements



Ethernet connection

Compact size and low power consumption

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Ease of Use
The SHF 78120 A is controlled over a standard Ethernet connection by an external computer (not part ofthe delivery). Every system comes along with the intuitive, easy to use BERT Control Center software(BCC). The BCC provides the user friendly interface for changing the device parameters.
Additionally, the instrument may be programmed remotely over the Ethernet connection for automatedtests and measurements. Please refer to the SHF BERT Programming Manual.

Graphical User Interface

Options
Option ISJ: Internal Sinusoidal Jitter Source
Several data communication standards require jitter tolerance and jitter transfer testing for sinusoidal jitterover a specified jitter frequency range. The optional internal sinusoidal jitter source allows stress tests forjitter frequencies ranging from 10 to 400 MHz. Jitter amplitudes up to 70 ps may be generated. The jitter
amplitude is calibrated depending on the jitter frequency and on the clock frequency.
It is enabled using the BCC GUI setting for internal jitter injection.

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Applications
SHF 78120 A
Clock Source

CLK/2Trig Out
RF Out

CLKBit Pattern
Generator

Clock InCh1 Data
Ch2 Data

DUT 1

Clock In

Error
Analyzer

Ch1 Data

High-Speed
Data Signals

Ch2 Data
DUT 2

Typical Multi-Channel Test Setup

Specifications – SHF 78120 A
Parameter

Symbol

Unit

Min.

fCLK

GHz

5Typ.

Max.

Comment

Clock Output (RF Out)Operating Frequency
Frequency Resolution

MHz38
1Frequency Accuracy–6Frequency Stability

10Frequency Stability AgingOutput Power Level–5Using internalreference–5Ambienttemperature 21°C

1010ppm
PoutdBm<1-10+8

Output Power Resolution

dB0.1

Output Power Accuracy

dB1Spurious Signals

dBc-20Phase Noise
Jitter (RMS)
Connector

dBc/Hz
JRMS

fstbd
400

On scope display (not1deconvolved)
2.92 mm (K) female

1

Measured with Agilent 86100A, 70 GHz sampling head and precision time base triggered by clock signal
from RF Out.
SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

Page 4/11Parameter

Symbol

Unit

Min.

Typ.

Max.

Frequency

GHz

1.25

19

Output AmplitudemVpp

400700CommentTrigger Out

2.92 mm (K) female

Connector
Option ISJ: Internal Sinusoidal Jitter Injection
Jitter Frequency

MHz10400

Jitter Amplitude

ps070

Modulation BandwidthMHz

0.11000

Modulation Amplitude

mVpp

01200

Maximum corresponds
to 70 ps jitter.

ps070

Peak-to-peak

External Jitter Injection

Jitter Amplitude
Connector

2.92 mm (K) female

Spread Spectrum Clocking
Modulation Frequency

Hz10100 kDeviation

ppm

020,000

Up/down/center

Ref InReference Frequency
AmplitudefrefMHz10Vpp

3.3Connector

SMA female

Ref Out
Reference Frequency

MHzAmplitude

Vpp10tbd

0.8Connector

SMA female

GeneralPower Consumption

WWeightKg

Operating Temperature°C

1025+12V switching power
supply is included

35

Ambient temperature

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Typical Output Signal Waveforms

Clock Signal at fCLK = 16 GHz, Pout = +4 dBm

Clock Signal at fCLK = 30 GHz, Pout = +4 dBm

Clock Signal at fCLK = 32 GHz, Pout = +4 dBm

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Output Amplitude
The following diagram shows typical amplitude measurement results using a power meter directly on theRF Out port for power settings from -10 to +8 dBm.

External Jitter Injection
For additional flexibility, arbitrary jitter modulation may be applied to the high-speed clock signal. Jitter isinjected by connecting a signal source such as an arbitrary waveform generator to the external modulation
input. The maximum jitter amplitude is 70 ps peak-to-peak with a modulation bandwidth of up to 1 GHz. As
an example, the jitter amplitude of 70 ps corresponds to a relative jitter amplitude of 2.2 unit intervals (UI)
at a bit rate of 32 Gbit/s.
The jitter amplitude is calibrated using the Trig Out trigger signal of the SHF 78120 A which remains jitterfree even if jitter injection is used.
In combination with an SHF Bit Pattern Generator and an Error Analyzer, the SHF 78120 A enables acomplete test solution for jitter tolerance tests as required by many telecommunication standards such as
100G Ethernet and 40 GBit/s OTN, FibreChannel, InfiniBand, PCI Express®, and Serial ATA. For furtherdetails please refer to the SHF application note „Jitter Injection using the Multi- Channel BPG“, available
online at www.shf.de.

Typical Jittered Signal Waveforms
The external modulation input can be driven by a function generator such as the Agilent 332XX family offunction / arbitrary waveform generators (AWG). The waveform characteristics of the AWG determine thejitter type of the SHF 78120 A.

 InfiniBand is a registered trademark of the InfiniBand Trade Association. PCI Express is a registeredtrademark of Peripheral Component Interconnect Special Interest Group (PCI-SIG).
SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Sine Wave on Modulation Input

AWG Setting
Waveform
Frequency
Amplitude

Sinusoidal jitter on 28 GHz clock,jitter amplitude 11 ps peak-to-peak.
Sine wave
100 kHz
70 mVpp

Gaussian-Distributed Noise on Modulation Input

AWG Setting
Waveform
Amplitude

Random jitter on 28 GHz clock,jitter amplitude 1.7 ps rms.
Noise70 mVpp

Square Waveform on Modulation Input

AWG Setting
Waveform
Frequency
Amplitude

Peak-to-peak jitter on 28 GHz clock,jitter amplitude 11 ps peak-to-peak.
Square100 kHz
70 mVpp

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Spread Spectrum Clocking
To meet the regulatory demands of electromagnetic interference several high-speed bus systems use aspread spectrum clocking (SSC) method. When SSC is enabled, the instantaneous frequency of the clock
signal varies periodically with time by a small amount, i.e. the clock signal is frequency-modulated. The
figure below illustrates the SSC frequency modulation with a triangular shape.
InstantaneousFrequency

Frequency
Deviation

Time1/Modulation Frequency

The principle of SSC is the periodic frequency modulation of a clock signal.

The key SSC parameters are the following:
fCLK

original clock frequency without SSC

δrelative frequency deviation (often given in percent or ppm, parts per million)

fjittermodulation frequency.

The parameters are directly accessible in the BERT Control Center software GUI or through remote
programming.
Depending on the relative position of the clock frequency and the frequency deviation, SSC can beclassified into three types: down, center, and up-spread. The figure below illustrates the three
configurations.

Down-Spread

Center-Spread

Up-Spread(1+δ) fCLK

Frequency(1+δ/2) fCLK
fCLK

fCLK

fCLK

(1–δ/2) fCLK(1–δ) fCLK
1/fjitterTime

1/fjitter

TimeTime

1/fjitterThree types of SSC.

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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SSC, effectively, broadens the spectral peak of a clock signal so that the maximum of the power spectral
density is reduced leading to less radiated emission. This is illustrated in the following spectra measured at
the output of the SHF 78120A for a 25 GHz clock with 30 kHz modulation frequency and 0.5% deviation. Notethat SSC does not reduce the total signal power of the clock. Rather, it redistributes the clock’s spectral
components as shown in the figure below.

Without SSC

With SSC

Peak Reduction

SpectralBroadening

SHF 78120 A clock spectrum with and without SSC.

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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Outline Drawing
SHF 78120 A Synthesized Clock Generator
Trig Out

Modulation In

Ref InRef Out50

50

Service

Ethernet

RF OutRF
On/OffOn/Off50

50

12V / 3A

17.6

35.4

50

47.1
44.9
42.1
3763.6

USB

28

19.8
2234.8
50.2
58

48
88

84.7
94
116

173.7
183.8

All dimensions are specified in millimeters (mm).

Input/Output Connectors
Connector NameDescription

RF OutClock output

Trig Out

Trigger outputModulation In

External jitter modulation input

Ref InExternal 10 MHz reference input

Ref Out

10 MHz reference output

Ethernet

Ethernet connection

ServiceService connector – Do not connectUSB

USB socket – Do not connect

SHF reserves the right to change specifications and design without notice – SHF 78120 A - V001 – 27th Jan. 2014

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