8-Load Pull Characterization

UniversityofColoradoatBoulder

9/30/2009

EfficientandLinearMicrowavePowerAmplifiers:

MicrowaveDesignTools Sparameters Only linear operation modeled Onlylinearoperationmodeled

8:LoadPullCharacterization

Nonlinearmodels Fit toanarrowcharacterization region Weaknonlinearitymodeled

Vgg

Vdd

Prof.Zoya Popovic JohnHoversten Contributingauthors: Dr.NestorLopez Dr.Srdjan Pajic MikeRoberg LukeSankey

Load pull characterization Loadpullcharacterization Empiricalmodel Measuredeviceresponseto largesignalconditionsSlide1 October2009

Zin @F0 @F2 @F3

Zout @F0 @F2 @F3

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EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder


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LoadPullVariablesandMeasurementsVariables Impedance Inputandoutputimpedance Fundamentalandharmonics

MechanicalTuners Mechanicallyactuatedtuning network Verywellcharacterized using VNA Mechanicallystableand repeatable Extremelylowloss

Measurements Input/outputpower Fundamentalandharmonics Linearity

Biaspoint(gate/drain) Inputpowerdrivelevel

DCpower Drainvoltageandcurrent DrainefficiencyPower Meter

Manufacturers:Maury,Focus MicrowavePower Meter Bandpass Filter Input Tuner Input Prematch Output Output Prematch Tuner Power Meter Bandpass Filter

Power Meter Bandpass Filter Input Tuner Input Prematch Output Output Prematch Tuner

Bandpass Filter

DUT

DUT

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LinearandEfficientMicrowavePowerAmplifiers:LoadPull Characterization

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SingleStubTunerSlugmovementinYprimarilychangesmagnitudeofgamma SlugmovementinXchangesphaseofgamma

TunerPowerLimitations Averagepower Resistivelossesincenter conductorcauseheating Expansion of metal damage to Expansionofmetal,damageto dielectricinconnectors(focusmicrowaves.com)

Peakpower Maximumstandingwave voltageisafunctionofpower andVSWR Highvoltagecancause breakdownbetweenslugand centerconductor LimitVSWRtoincreasepower

10 Breakdown Power [W W]

3

Power Required to Achieve Specified Field in a 5mil Gap

Pulsedmeasurement 10usec/100usecpulsekeeps averagepower10dBlower thanpeakpowerOctober2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide5 October2009

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2

10 0.6

1

25kV/cm 30kV/cm 35kV/cm 40kV/cm 45kV/cm 0.65 0.7 0.75 0.8 0.85 Gamma 0.9 0.95 1


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TunerNotes Frequencylimitation xrangeandprecisionis relatedtophase Limitsperformanceover frequency

HighPowerMicrowaveDevices Parallelizedunitcells Capacitanceadds Increasedcurrent,same voltage Drivesoptimaloutput impedancelower

Lossreducestuningrange LossbetweentunerandDUT limitsmaxVSWR

Harmonictuning Multislug,multicarriage tunerdesigns Harmonicwaveinjection Triplexers

Technologyvariationand internalmatching MOScap/wirebond LCL networks t k

Typical100W/2GHz/32Vdd deviceshave~1ohmoutput impedance

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PackageEffects Analyticalderivedoptimalimpedanceisdefinedatthe devicecurrentsource(onthedie) Package transformation is significant Packagetransformationissignificant Width,height,substratediscontinuities;bondwires

Input/Output PreMatch50to15ohmtransformerconcentratestunerconstellation Lengthoflinerotatesconstellation

Loadpullandcircuitdesignreferenceplaneistypicallyat packageedge Packagecanbedeembeddedfromresults

FullwavesimulationrecommendedS11 S22

Port2S12 S21Power Meter Bandpass Filter Input Tuner Input Prematch Output Output Prematch Tuner Power Meter Bandpass Filter

Port1

DUT

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HarmonicPreMatch Singleslugtunersproducearbitrary2F impedance Highefficiency modes are critically High efficiencymodesarecritically dependentuponharmonictermination Forceharmonicimpedanceswithprematch

OriginalConstellation

IncorporateBiasintoPreMatch Biascanbesuppliedexternally(A) Stabilitymayrequireabiasteecloseto thedevice(B) Highpowerdevicescommonlyoscillate around100MHzduetobiasteelocation anddesign Biasteeinprematchwilladdloss

Packagetransformationhasalargeeffect onterminationsat2F,3F,etcOpen 90 at2F DUT Openat2F Parallelcombination: 2F:Short F0:j*Zo,stub*wOctober2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide11

Prematched Constellation F0 2F

Desiretransistorcharacterization independentofbiasnetworkdesignInput Tuner Input Prematch Output Output Prematch Tuner

DUT

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B

B

ASlide12



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PreMatchCalibration

Input Prematch

Output Prematch

DUT

ReferenceplaneisattheDUT,notthefixture MustdetermineSparametersofprematch p p Simulationisnotaccurateenough Variationofpassivecomponents Measurementofactualhardwareisrequired

Impedance Verification

TRL:ReflectStandard (Ver.Block+Open) TRL:ThruStandard (Ver.Block+Ver.Block)

Verification Verification Block Block

TRL:Line1Standard (Ver.Block +Line1 +Ver.Block) TRL:Line2Standard (Ver.Block+Line2 +Ver.Block)

Impedanceverificationtechnique Solvethesparametersofaverificationblock usingThru Reflect Line(TRL)algorithm using ThruReflectLine (TRL) algorithm Measuresparametersoftheverificationblock cascadedwiththeprematch Deembedverificationblockfromthecascade toobtainprematchonly

Input Prematch

Verification Block

InputPrematch +Ver.Block OutputPre match+Ver.Block Output Prematch + Ver Block

Verification Block

Output Prematch

OutputPrematch +DUT+ InputPrematchSlide13 October2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide14

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TRLBlockDesign Continuousmicrostrip transition betweenverificationblockandpre match Identicalwidthandsubstrate

TRLBandwidth Operationfrom220GHz Linesmustbe30150 degrees Foreffectivedielectric constant3.25 Twolinesarerequired (2GHz7GHz,7GHz20GHz)Electrical Degrees of TRL Line Standards over Frequency 200

TRLequationsfailwhenthrustandard hasverylowtransmission AvoidresonanceinTRLblocks Tapersachievebroadband transformations

150 Degrees [deg]

TRLstandards Reflectmaybeopenorshort,quality notcritical Line must be between 30 and 150 Linemustbebetween30and150 degreesoverfrequencyofinterest Multiplelinestandardscanextend range Characteristicimpedancemustbewell known(relatedtomicrostrip transition width)

100 6mm 8mm 10mm 12mm 14mm 0 5 10 15 Frequency [GHz] 20

References A il AgilentAN12879In AN 1287 9 I FixtureMeasurements UsingVectorNetwork Analyzers Engen andHoer,MTT1979Slide15 October2009

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0

ImportanceofverificationOctober2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide16


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BreakApartFixture Repeatability Considerbreakapartfixturedesign Onlyonecopyoftheprematch y py p eliminatesvariationduetopassives, soldering,andmanufacturing

InputBlock Preamp/Source Needsignificantoutput powermargintoovercome 3dBpadandtunermismatch 3dB pad and tuner mismatch loss Lowharmoniclevelsrequired

Attenuator 3dBattenuatorprovides minimum6dBreturnlossout of band ofband Preventsoscillation

Heattransfer Someimpedanceregionsproduce highheatdissipation

Circulator Isolatepowermeasurement andpreampfromtuner variation IsolateDUTfrompreamp outputimpedancevariation p pPower Meter Bandpass Filter Input Tuner Input Prematch

Coupler/Bandpassfilter Measureinbandforward powerInputblockmismatchwillimpact p constellationandpowermeasurements!Power Meter Output Output Prematch Tuner Bandpass Filter

Flexibility Accommodateavarietyof transistordimensions i di i

DUT

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ReflectionLossandInputPower Mismatchbetweenblocks Reflectionlossateachblock varieswithtunerposition varies with tuner position Correctpowermeasurement requirespreciseknowledgeof allSparm Sparm errorscauseDUT impedanceerrorsandpower measurementerrorsatinput andoutput

VNACalibration SOLTforhighaccuracynear50 ohms Most commonly used VNA MostcommonlyusedVNA calibrationmethod

PoweravailabletoDUT Whatwecallinputpoweris actuallythepowerthatwould bedeliveredtotheDUTifno powerwerereflected (conjugatematch) Reflectedpowerisunknown, becauseDUTinput impedanceisunknown

TRLcalibrationforhighVSWR measurements Commerciallyavailable Highprecision,otherwiseidentical toverificationkitTRLstandards

TransducerGain: Pdelivered,load / Pavailable,input /PInput Prematch

Input Block

Power Meter

Input Tuner

DUT Available Reflected Delivered

Always verify VNA calibration AlwaysverifyVNAcalibration beforemeasuringloadpullblocks PoorVNAcalibrationor measurementpracticeistypically thecauseofloadpullerrors

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OutputBlock OutputAttenuatorChain DissipateDUTpeakand averageoutputpower Si t Sizetoprotectequipment t t i t frommaximumpossible powerlevel($$$) Sizetoavoidvariationwith temperature Todissipate30dB/150W: 10dB/200W+20dB/50W 30dB/150W

CalibrationandConfidenceCheck SParametermeasurements Input/outputblock Tuners,atmanyxy positions Prematch Pre match

Coupler/Bandpassfilter Measureinbandforward power

S Spectrumanalyzer l Watchforoscillation Measureharmoniclevels Measurelinearity

Errorsources Calibrationmeasurements Mechanicalinstability Powernonlinearity,thermalinteraction Voltage/currentmeasurement

Highefficiency DCpowermeasurementSparametererrorscausepowermeasurementerrorswhichvarywithimpedance!MeasuresystemwithnoDUTtoverifyconsistentoffsetvs.impedance. Measure system with no DUT to verify consistent offset vs impedancePower Meter Bandpass Filter Power Meter Bandpass Filter

Power Meter Bandpass Filter

Outputblockmismatchwill impactconstellationandpower measurements!Input Tuner Input Prematch Output Output Prematch Tuner

InputOffsetInput Tuner Input Prematch

OutputOffsetOutput Output Prematch Tuner

Power Meter Bandpass Filter

DUT

DUT

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LoadPullProcedure Smallsignal Setreasonableloadimpedance Sourcepullforpeakgain Load pull for gain (with constant Loadpullforgain(withconstant inputpower) MatchSSperformancewith datasheet,Sparms,orNLmodelif possible

Stability Oscillation Candamagedevices Addserroneousdata C id Considermonitoringspectrum it i t toflagdatapoints with oscillation

Measurementsateachpoint Input,outputpower Vdd,Idd

Testconstellationsize Constraintoaninteresting region Closecontours,retuneprematch ifrequired Avoidextremetunermismatch (VSWR>10:1)NITX050 - 28V

Largesignal,constantinput power Slowly increaseinputpower Repeatloadpullforoutputpower andefficiency Unstableregions Highpowerdissipationregions

Unstableimpedanceregions Identifyaspossibleinsmall signal Tunerpassesthroughwide impedancerange ConsiderreducingDC/RF g / powerwhiletuning

j10 j5 j20

Pout [W] D [%]

Powersweepateachimpedance point Terminatesuponreachingdesired gaincompressionOctober2009

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j2

56 73

Largesignal,gaincompression

33 65

DrainDCsupplycurrentlimit8273

3 23 28

48

38

65

82

0

2

5

10

20

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Cancause lowfrequency oscillation Considersettingcurrentlimit wellaboveexpectedcurrentOctober2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide24

43 43



5 65 483 438 48 48 3 39 2839 31 31 23

13 13 8 18

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LoadPullLinearity TwotoneM MeasureIMD3andIMD5 IMD3 d IMD5 Varyingtoneoffset Linearityandoutputpower areopposed

PrototypeDesignVerification Selectimpedanceto satisfypower,efficiency, gain,linearity gain linearity requirements Buildprototypefor desiredimpedances Useimpedance verificationtoconfirm desiredimpedances Useloadpulltoverify thatprototypeisoptimal solutionSlide25 October2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide26

Complexmodulation E g WCDMA E.g.W CDMA MeasureEVMandACP Realworldperformanceof thedeviceOctober2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder

ManualXBandHarmonicLoadPull

ExampleProcedure1. Gatherdeviceinformation 2. 3dpackagemodelingif required 3. Approximateexpected loadimpedanceforpre matchdesign 4. Designprematchcircuits withharmonictermination andbiasnetworks 5. DesignTRLverificationkit 6. Prematchcalibration 7. Loadpullcomponent calibration 8. Loadpullsystem verificationand confidencechecks 9. Small andlargesignal sourceandloadpullover desiredconditions 10. Prototypedesignand verification

Loadpullcharacterizationisachallengingprocessrequiring carefulplanning,calibration,andmeasurement!October2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide27 October2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide28


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DiscussionPoints Howlongdoesittake? Typesofmeasurements includedinloadpull Howtodefinethebest impedance? Willtheprototypeexhibit thesameperformanceas thetransistorunderload pull?October2009

Loadpullexamples RFMDFPD3000inSOT89Package(1W)Discretedeviceloadpull,notcloseto50

Setup,calibration, instrumentcontrol,and verification Power,efficiency,? Tradeoffsindevice performance Loadpullreferenceplane atdie,package,or prototypeterminalsSlide29

TIPALNAforISMbandwirelesstransceiver rangeincrease(200mW)Verifyimpedancethatwasexpectedtobearound50

Diodesourcepullforwirelesspowering p p g rectifierantennadesign(100W)SpecializedmeasurementwithDCload


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PackagedRFMDFPD3000 TRLcalibrationstandardsanddeviceinfixture;noteharmonicstubs incalibrationstandards Mr.MichaelRobert,UCBoulder

PackagedRFMDFPD3000:SourcePull First,sourcepullisperformedtodeterminetheoptimalimpedancetopresentto thepackagegate Wanttomaximizethepowerdeliveredtothedevice Sourcepullwasperformedwithanarbitraryloadimpedanceof15.00+j1.43 Peaktransducergainoccurswhen8.42+j5.57 ispresentedtothepackagegate

DeliveredOutputPowerOctober2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide31 October2009

TransducerGainSlide32



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PackagedRFMDFPD3000:LoadPull Loadpullisperformedtodetermineoptimalimpedanceatthedrainofthepackage Wanttomaximizethepowerdeliveredfromthedevice,transducergain,etc Loadpullwasperformedwiththeoptimalsourceimpedanceof8.42+5.57 Peakoutputpowerandtransducergainoccurwhen9.35 j3.67 ispresentedto thepackagegate

IMSbandTIPALNAloadpull CC2591isaPALNA(switched)used toboostrangeforaChipcon TI 2.4GHzwireless transceiver/microcontroler t i / i t l Impedanceforoptimalpowerand gainquotedat50 butneedstobe verified 200 differentialoutputbalun LDB182G4520C110(Murata)used todriveinput(shouldhavebeen 100 ) Balun has1.4dBinsertionloss Themeasurementisaccurateto betterthan+/ .5dB,andpreciseto lessthan.1dB. Mr.LukeSankey andMr.Steve Dunbar(TI)Balun R LoadpullTRLcalibrationstnadards TICC2591PALNA

L T

DeliveredOutputPowerOctober2009

TransducerGainSlide33 October2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide34


Load/sourcepullresultsforTICC2591Optimaloutputimpedance14.56j6.36 (3.6Vbiasand10dBm inputpower). Optimalinputimpedance~55.

Schottky dioderectifiersourcepull Nonlinearimpedanceofdioderectifierdependsoninputpower, DCload,RFmatch,frequency Neededforoptimizingwirelesspoweringcircuitsandrectennas Mr.Erez Falkenstein,UCBoulder

Pmax=12.94dBm,Gmax=22.83dB 1st contour(12dBm,22dB)October2009

Pmax=12.91dBm,Gmax=22.78dB 1st contour(12.5dBm,22.5dB)Slide35 October2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide36



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Schottky dioderectifiersourcepull TRLcalibrationandtestcircuitsusedinthesourcepull.Thetest circuitisnarrowbandanddesignedtomovetheimpedanceofthe diodetowardsthemiddleoftheSmithchartatthedesignfrequency.

Schottky dioderectifiersourcepull VNA/PNAmeasurementinadequateforrectifierdesign: thediodeimpedancecanbefoundonlyforaspecificRFprematching conditionatthediodeterminals; rectifiedpowertrendsforvaryingRFloadconditionscannotbe obtained; fordifferentincidentpowerlevels,thematchtothediodevaries,andso theexactpoweracrossthediodeisnotknown; itisnotstraightforwardtoincludeapoweramplifierandavariableDC load.

Z diode = RF DC =HarmonicbalancesimulationcircuitOctober2009 EfficientandLinearMicrowavePowerAmplifiers UniversityofColoradoatBoulder Slide37 October2009

VRF = Z ( f , PRF ,in ) I RF

PDC = ( f , PRF ,in , RL , DC ) PRF ,in


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Schottky dioderectifiersourcepull ConstantPDC rectifiedplotted(contours)fortwodifferentDCloads, ataconstantinputpower(5dBm)andf=1.96GHz. Red:loadpull;Blue:Harmonicbalance(ADS)

Schottky dioderectifiersourcepull Otherfrequencies:900MHz,2.4GHz,5.8GHz Otherdiodeconfigurations

Singlediode

50 DCload,Pin=5dBmOctober2009

500 DCload,Pin=5dBmSlide39 October2009

5.8GHz Pin= 5dBm R=25 Idc=450mA Zopt=28j25

5.8GHz Pin=0dBm R=75 Idc=705mA Zopt=38j29Slide40




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Schottky dioderectifiersourcepull andrectenna design Nowwecandesignoptimalantennaimpedancefora rectenna (e.g.foracoffeecupthatcanbepagedinthedark) Examples:dipoleat900MHzwithinductivediode matching;patchwithtwoports(dualpol) matching; patch with two ports (dual pol)

SMS7630079LF,915MHz Zopt=200+j100 Voc=0.69Vjustdiode Voc=0 69V just diode Voc=1.1Vwithinductor

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