Montreal, CABoston, USA

Cardiff, UK

RAPID
Shengie Gao
Sajjad Ahmed
Bryan Hosein
Tudor WilliamsSimon Woodington
Randeep SainiBaoli Tian
10/28/2016

INNOVATION SUPPORT DEPENDABILITY

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Montreal, CABoston, USA

Cardiff, UK

The Focus Group in 2016
• FOCUS-Microwaves Inc., Montreal, Canada• MESURO Ltd., Cardiff, UK• AURIGA PIV Tech. Inc., Boston, USA

10/28/2016

INNOVATION SUPPORT DEPENDABILITY

2• World map FOCUS
AURIGA

ELECTRO-RENT

MESUROAURIGA EUROPE
FOCUS EUROPE

AMTECHS
FOCUS CHINA

FOCUS GROUP
Associate

GLOBALLY PRESENT
10/28/2016

INNOVATION SUPPORT DEPENDABILITY3

24 hrs On Line Help

10/28/2016

INNOVATION SUPPORT DEPENDABILITY

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Introduction•Outline– System Description• General principle• S-Parameter/Power Calibration• RAPID Loop Calibration– Tuning Accuracy• RAPID system• Referenced to commercial VNA– Device Testing• Comparison to Passive Load-Pull system– Long Term Testing• Raw performance• With internal “live” correction– Measurement Speed– Modulated Measurements– API and Programmability– Conclusions
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System Description

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System Description•••

The Rapid Load-pull Tuner (RAPID) is a programmable digital, PXI-based, feedback active load-pulltuner that maximizes throughput of a load-pull bench.
The output port of the DUT is fed via a dual-directional coupler to a down converter module.
The base-band data is then processed in an FPGA module and sent to the up converter to form
the injected signal.

DUT

Optional PassiveTunerAs the system contains two RF receivers it can accurately measure power and
impedance removing the need for power meter and/or VNA in the load-pull testbench.
7Calibration of theRAPID

START

1. Define Frequency
list formeasurements(1..n)

2. One Port Vector
calibration and verification

Create a newcalibration fileCalibration File

3. RLPT Loop calibration

Append to existing
calibration filewhen finished

Repeat RLPT Loopcalibration if neccesary

4. (OPTIONAL)
RLPT Loop verification

S-Parameter & Power Calibration• The system can measure the forward and reverse travelling waves, so unlike a
passive tuner calibration, there is no requirement for an external VNA.
• The first step is therefore to perform a one or two port VNA calibration, this isperformed as a standard SOL, SOLT, or TRL cal at the desired reference plane.
• A power meter can then be used to calibrate for accurate power measurements,by attaching a power meter to the reference plane.
Hardware setup

S-Parameter/Power Calibration• The RAPID calibration utility offers a guided one-port calibration with built-inverification tools for power and s-parameter measurements.
RAPID Calibration Utility

RAPID Loop Calibration• The loop calibration must be performed before attaching the device.
• It is used to calculate the error coefficients associated with the feedback loop.
• Once these error coefficients have been found the user can accurately set any
impedance on the smith chart without the need for interpolation.

Hardware setup

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RAPID Loop Calibration• The loop calibration is an automated process and the calibration coefficients arecalculated and saved within the RAPID loop calibration module of the RAPID
Automation suite software.
• The software also includes a verification step to test the accuracy of the loop
calibration.

RAPID Loop Calibration

Verification tools

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Tuning Accuracy

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Active Load-Pull Measurements
Ability to Control Gamma Load

• After running the loop calibration, verification measurements are carried out withimpedance measured by the rapid hardware.
• A power amplifier is included as part of the loop.

Active Load-Pull Measurements
Ability to Control Gamma Load

• The following plots show the error between target and achieved impedance.

Excellent agreement between set
and measured impedance*Note Passive tuners are generally
specified to >40dB repeatability

Comparison to Commercial VNA• Measurement Configuration is shown below.
• VNA and RAPID are calibrated at the same reference plane for direct comparisonof measured s-parameters
10 MHz10 MHzVNA

R1

R2

RAPID Hardware

DUT

R1

R2Calibration
Plane

RF Source
10 MHz

DUT orMeasurement Standard

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Comparison to Commercial VNA
Smith Chart view

• Here we show the difference between ZVA and RAPID
measurements both on the Smith chart and expressed as
error in dB-scale format.
Error values (in dB) when comparing Gamma
measured on VNA and RAPID receivers

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Device Testing* Note No Source tuning has
been performed during
testing. The device is a 50ohm matched part.
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50 Ohm power-Sweep: Focus Passive to RAPID• This comparison measurement shows results of a 50 ohm power sweep
conducted with a Focus passive load-pull system with integrated power meter
behind the tuner and the RAPID unit with the power measurement performed
within the calibrated unit.
Excellent agreement with theimpedance set to 50 ohms on
both systems.

Power-Sweep at 0.4<0°: Focus Passive to RAPID• This comparison measurement shows results of a power sweep at a non-50 ohm
load-pull position conducted with a Focus passive load-pull system withintegrated power meter behind the tuner and the RAPID unit with the power
measurement performed within the calibrated unit.
Excellent agreement with theimpedance set to 0.4<0° on
both systems.

Measured Contours: Focus Passive to RAPID• Next a power contour is plotted from the data from each of the systems.
• Measurement was performed for a constant available power of 3dBm.

RAPID System

Excellent agreement inmeasured contours
between the two systems.

Focus Passive

Long Term Testing(Raw Performance)

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Active Load-Pull: Long Term Test (1)••Long term test plan was to run a grid of 62 impedances covering the smith chart, over apower range of 30dB in 1 dB steps every 30 minutes for a period of 48 Hours.
The results shown on a Smith chart for the entire sweep of 130,000 measurements with aZVA-8 VNA and the rapid system are shown below. No live correction is employed.

RAPID SystemVNA

Active Load-Pull: Long Term Test (2)• Plot below shows the difference in dBs between the target and measured
impedance using the RAPID hardware.

Long Term Device TestingWith Live correction

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Long Term Stability

65 Hour Test (with live correction)• The test is now repeated, this time with a DUT present• Power and impedance were swept for a 65 hour period, this time we employ thelive correction.
• Desired tolerance is set to 50dB.

Long Term Load Stability: 65 Hour Test
• With live correction employed it is clear that a much more accurate impedance
can be obtained under long term tests..
Average Repeatability
66.45dB
Worst Case
48.4dBStability of Power Measurement – 65 Hour Test
• During the same test this looks at stability of Power measurement.
• Plot below shows power measured at the optimum impedance with ameasurement every 30 minutes for a period of 65 hours.

Average Power = 10.649dBm
Peak Power = 10.683dBm
Min Power = 10.606dBm
Deviation <± 0.04dB

Contour plots, Before and After 65 Hour Test
• Another way to look at drift in the measurement is to look at measured power
contours at the start and at the end of testing, as shown below no drift is seen.
Start of Test

After 65 Hrs

Measurement Speed30Measurement Speed• The speed of a CW load pull is approximately: 5 ms per load synthesized at 1k
IFBW (200 points/second). This includes impedance synthesis and output power
measurement.
• The above time increases to approximately 15 ms per point when using full vector
correction load pull (input and output DUT measurements: a1, b1, a2, b2). Fromthese measurements power gain, gammaIn, gammaLoad, output power, delivered
input power, and AM/PM can all be calculated.
• Using full NI-PXI based instrumentation (including source and DC measurement),and full vector correction load pull power measurements, the DUT efficiency canalso be determined. This increases the total time per load pull point toapproximately 19-20 ms (50 points/second).

Modulated Capability

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Modulated Measurements• As the active loop has 100MHz of instantaneous bandwidth it is also possible toperform real time modulated measurements.
• There are two main applications for this outlined below:
1. Full Active Solution• Ability to present a constant static wide-band load over a full modulatedbandwidth.
• Ability to emulate a real matching circuit over a wide bandwidth.
2. Hybrid Solution• Ability to De-skew impedance over the full modulated band.
• Ability to emulate a real matching circuit over a wide bandwidth.

Measured Signal

Injected Signal

Circuit Emulation
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Modulated Measurements
Wide-band impedance over swept impedance,
10 tones 1MHz steps. Constant impedance
held over 10MHz Bandwidth.

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API and Programmability
RLPT Automation Flow chart

NO

Enable RF on
external Sig Gen

YES

enableRFOutput(1)INITIALIZATION

START

createFromCalFile()

setCWFrequency()

External
Driver RFON?

TUNNING

Set AnotherTarget Gamma?

YESNO

setGamma()

Measure poweror gamma?

NOYES
getPower()

CLOSING• The Focus RAPID Automation
Suite software contains a fully
documented impedance control
library available to use on theclient PC using ActiveX andMicrosoft .NET framework DLLs.
• The library is thus compatible withmost modern programming
platforms e.g.
• NI Lab View
• Microsoft Visual Studio: C#,
C++, Visual Basic• MATLAB• etc• This allows the user toprogrammatically move the tuner
to any impedance and de-embedto the DUT reference plane.

enableRFOutput(0)getGamma()

disconnect()

triggerMeasurement()

END

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Conclusion•••••The RAPID system is an advanced load-pull tuner that can replace the passive tuner
and some measurement equipment in your load-pull bench.
We have shown the ability to accurately measure impedance and power, even overlong periods of time (tested up to 65 hours).
CW measurement speed (50-200 pts/second depending on measurement
complexity), is orders of magnitude faster than existing load-pull techniques.
System is also suitable for modulated measurements with 100MHz of instantaneous
bandwidth offering the ability to de-skew passive measurements, present wideband active loads and/or emulate circuits over modulated bandwidth.
A full programming library (API), compatible with most modern programming
environments is available for tuner automation.

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