Determing Amplifier Nonlinearities by using “Real-World ... · Determing Amplifier Nonlinearities...

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2 MAR | Re | 08/00 |

11MAA | 10.03 | MW 1 Nonlinear Measurement TechniquesEuropean Microwave Week 2003 - Munich

Determing Amplifier Nonlinearities by using “Real-World“ SignalsEuropean Microwave Week 2003

Martin Weiß, [email protected]

Nonlinear Measurement TechniquesEuropean Microwave Week 2003 - Munich

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FundamentalsTechniques

Swept Power Measurement

Two Tone Measurement

Real SignalAny Stimulus

Real SignalModulated

Conclusion

Table of Contents

Techniques and FundamentalsDifferent Measurement Methods:

- Swept Power Measurement- Two-Tone Measurement- Measurement with a real signal – Any Stimulus- Measurement with a real signal – Modulated Stimulus

Conclusion

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Conclusion

Techniques and FundamentalsProblem

Ref -12 dBm Att 0 dB*

**

*2 RMVIEW

* B SGL

RBW 10 kHz

VBW 100 kHz

SWT 10 s*

Center 1 GHz Span 4 MHz400 kHz/

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

CH PWR -11.32 dBm

ACP Low -35.23 dB

ACP Up -35.55 dB

Ref -12 dBm Att 0 dB

RBW 10 kHz

VBW 100 kHz

SWT 10 s*

***

*

Center 1 GHz Span 4 MHz400 kHz/

1 RMVIEW

BSGL

-110

-100

-90

-80

-70

-60

-50

-40

-30

-20

CH PWR -11.46 dBm

ACP Low -65.86 dB

ACP Up -65.85 dB


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Conclusion

Techniques and FundamentalsGoals

Predistortion Method:DigitalPredistortion

Measure:AM/AM and AM/PMcompression curve

Model:Polynomial approximation

Goal:Low ACP and EVM values

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Conclusion

Swept Power MeasurementResults with a Network Analyzer

Increase powerFAST

Increase powerSLOW

Decrease powerFAST

Decrease powerSLOW

Pin

Pin - Pout


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Conclusion

Two tone measurementPrincip of Measurement

Measurement with a two-tone signalWhich modulation frequency fm must be selected?

f0 f0 + fmf0 - fm

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Conclusion

Two tone measurementTypical Result with different Modulation Frequencies

Tones

K3

K5

Colors:Different modulation frequencies


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Conclusion

Two Tone MeasurementThe new R&S Vector Signal Generator SMU

For more information, visit our stand

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Conclusion

Results with different test signalsCW – Multi-Tone - Pulse


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Conclusion

Results with different test signalsConclusion

The crest factor of the stimulus signal has a significantinfluence on the measured AM/AM and AM/PM compression curve

CONSEQUENCE:Measurements need to be performed on a signalwith the same bandwidth and crest factor as in real operation conditions

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Conclusion

Real Signal – Any StimulusTest Setup Overview – R&S Software AmpTune


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Conclusion

Real Signal – Any StimulusMeasurement Steps

Generate the test signal or load it via fileAdjust the DUT input level for the desired RMS output levelDownconvert the RF signal to IQ baseband and sample itPerform a synchronizationCalculate the AM/AM and AM/PM modelPredistore the test signalVerify the predistortion effect

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Conclusion

Real Signal – Any Stimulus Available Test Signals

Bandlimited Noise (generated internally)Two Tone (generated internally)Signals from WinIQSIM (import via file)Signals from many simulation tool (import via IQWizard)NPR (Noise Power Ratio) signals(import via IQWizard, generation via NPR tool)

http://www.rohde-schwarz.com -> Application Notes


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Conclusion

Real Signal – Any Stimulus Key Features

Precise timing synchronisation and delay calculationAuto-leveling of the DUT output powerMeasurement of RF-to-RF devices (Amplifiers, …)Measurement of IQ-to-RF devices (direct-upconverter, …)Support of all R&S Signal Generators and IQ Sources(AMIQ, SMIQ-B60, SMIQ, SMU)Support of all R&S Signal and Spectrum Analyzers(FSIQ, FSP, FSU, FSQ)HTML Measurement Report including curve coefficientsFree-of-charge software

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Conclusion

Real Signal – Any Stimulus Signal Processing


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Conclusion

Real Signal – Any Stimulus AM/AM and AM/PM Measurement and Predistortion

AM/AM curve AM/AM predistortion

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Conclusion

Real Signal – Any Stimulus Predistortion Results with 8 MHz signal, 10 dB Crest

Withpredistortion

-61.23 dBALT1 Up

-61.12 dBALT1 Low

-58.28 dBACP Up

-58.09 dBACP Low

-11.25 dBmCH Power

Withoutpredistortion

-61.85 dBALT1 Up

-61.73 dBALT1 Low

-44.47 dBACP Up

-44.46 dBACP Low

-11.26 dBmCH Power

RF AmplifierCDMA signal, 8 MHz BW

-80

-70

-60

-50

-40

-30

-20

-10

-24,0 -20,0 -16,0 -12,0 -8,0 -4,0 0,0 4,0 8,0 12,0 16,0 20,0 24,0

Frequency Offset [MHz]

Leve

l [dB

m]

PredistoredOriginal


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Conclusion

Real Signal – Any Stimulus Free software AmpTune from Rohde & Schwarz

http://www.rohde-schwarz.com/AppNote/1MA27

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Conclusion

Real Signal – Modulated Measurement with Rohde & Schwarz FSQ & FSQ-K70


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Conclusion

Real Signal – Modulated Principals of Operation – Vector Signal Analysis

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Conclusion

Real Signal – Modulated Measurement with Rohde & Schwarz FSQ-K70


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Conclusion

ConclusionOverview over the Presented Methods

FSQFSP/U/QFSP/U/Q

NetworkAnalyzer

ZVxAnalysator

NOYESNONOMeasurementReport

Vector Mod.Signal

AnySignal

TwoTone

SingleCarrierStimulus

---AmpTune---Software

SMIQ / SMUSMIQ / SMUSMU

---

Generator

NOYESNONOAutomaticPredistortion

HIGHHIGHHIGHLOWMeasurementBandwidth

YESYESPARTLYNOSuitable forAmplifier Test

Real SignalFSQ-K70

Real Signal„AmpTune“Two ToneSwept Power

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Conclusion

Thank you for your attention!For additional information, please visit our stand

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Determing Amplifier Nonlinearities by using “Real-World ... · Determing Amplifier Nonlinearities...

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