電子科學與技術外文翻譯

科學與技術外文翻譯Designofintegrated1.6GHz,2WtunedRFpoweramplifierAbstract：ThispaperdescribesthedesignofanintegratedtunedpoweramplifierspecifiedtooperateatInmarsatsatelliteuplinkfrequenciesfrom1626.5to1660.5basictopologyoftheamplifierliesontheparalleltunedinverseclassEamplifierthatismodifiedbyplacingtheDC-blockingcapacitorintoanewpositionandbyadjustingthesizeofthecapacitortoimprovestabilitybelowthedesiredband.Further,thenewpositioningreduceslossesbetweendrainandload.Thehighcurrentsflowinginthecircuitmadeitnecessarytousewideinductorwidthandhigh-Qfingercapacitorsintheon-chipresonator.TheamplifierwasimplementedasaGalliumArsenide(GaAs)integratedcircuit(IC)thatdelivered2Wofoutputpowerwhilethedrainefficiencywasca.56%.Measurementsincludedsourceandloadpullstofurtherimprovetheperformanceoftheamplifierandtoinvestigatethestabilityatsmallinputdrivelevels.Keywords:InverseclassE?Power-oscillation?Biasnetwork1IntroductionTheusabilityoftraditionallinearamplifiersintoday’shighpowermunicationssystemsislimitedduetotheirlowefficiency.ThisfacthasdriventheinterestofresearchtowardsmoreefficientamplifierssuchasclassE[1–3]andinverseclassE[4].Also,thedemandofhigheroutputpowermeanshigherpeakcurrentsandvoltagesinthedrainorcollectorcircuits.Thiscreateshighrequirementsforbothmaximumbreakdownvaluesofthetransistorandtothepassivecircuitryofthemonolithicmicrowaveintegratedcircuit(MMIC).TheeffectoflimitedconductivityandlimitedcapabilitytocopewithheatcanbeminimizedthroughcarefuldesignofMMIC.Further,emergingtransistortechnologiesseemtowithstandlargercurrentdensitiesandpeakvoltages[5],andtherefore,thechoiceoftechnologyisincreasinglyimportantwhendesigninghighpowerdevices.Theaimofthispaperistoshowexperiencesrelatedtothedesignofswitchinghighpowerradiofrequency(RF)amplifiers(PA)withintegratedoutputpulseshaping.InthesecondchaptertheintroductiontoclassEandinverseclassEoperationisrevisitedandthedifferencesbetweenthetwotopologiesarethirdchapterdescribesthedesignoftheinputandoutputcircuitry,stabilizingcircuitsandprovidessometipstominimizetimingdifferencesattheinputofamulti-fingertransistor.Thefourthchaptershowsthefinalschematicandaphotooftheimplementedchip.Themeasuredperformanceisreportedinchapterfivebyusingbothbasicsingletonemeasurementequipmentandamodernloadpullsystemusingmulti-purposetuners(MPT).Thelastsectionprovidesasummaryofthearticleanddiscussionoftheissuesrelatedtostabilizingcircuits.2ClassEandinverseclassEamplifiersClassEandinverseclassEareregardedasswitchingamplifiers.Ideally,inbothofthemthetransistorisdriveneitheronoroffandthisswitchingoperationproducesaseriesofvoltageandcurrentpulsestotheoutput.Thesepulsesarephaseshiftedandthereforedonotoverlapwitheachother.Idealnon-overlapcausesthetransistortooperatewithdrainefficiencyof100%.ClassicalclassEdrainwaveforms,normalizedtoDCvaluesofsupplycurrentandvoltage,areshowninFig.1.Thesolidlineisnormalizeddraincurrentwaveformandthedashedlineisnormalizeddrainvoltage.TherequirementforoptimaloperationinclassEiszerovoltageswitching(ZVS),wherethedrainvoltageanditsderivativegoestozerojustbeforethetransistorstartstoconduct.IninverseclassEthewaveformshaveswappedplacessothatthesolidlinewaveforminFig.1isthedrainvoltageandthedashedlineisthedraincurrent.Theoptimaloperationisalsochangedtozero-currentswitching(ZCS),wherethecurrentanditsderivativegoessmoothlytozerobeforethetransistorentersnonconductingphase.AdvantagesofinverseclassEoverclassicalrealizationarethatthedrainpeakvoltagesarelowerthaninclassicalclassEandtheinductancevaluesintheoutputcircuitryaresmaller,whichcansaveareainaMMICchipimplementationandcanusuallygivesmallerelectricalseriesresistance(ESR)[4].Also,thepossibilitytoacmondateseriesinductanceasapartofresonatingcircuitryisuseful,sincetheparasiticreactancescancauseundampedresonancestodrainwaveforms[6,7].TheseadvantageswerethereasonsforchoosinginverseclassEtopologyasastartingpointforourinvestigation.However,thetunedimplementationisnottraditionalinverseclassE,althoughithassimilarpulsedoperation.3Designoftunedpoweramplifier3.1GaAsICprocessTheICprocessusedisaTriquintSemiconductor’spseudomorphichighelectronmobilitytransistor(pHEMT)processnamedTQPED.Theprocessutilizesbothenhancementanddepletionmodefieldeffecttransistors(FETs)with0.5lmlengthopticallithographygates,butinourcaseweusedonlydepletionmodetransistors.Theavailabledepletionmodetransistorshaveatransitionfrequency(Ft)of27GHz,drain-gatebreakdownvoltageof15Vandnominalpinch-offpointof-0.8V.TransistorsmodelsusedareTOM3FETmodels.Thereareseveralotherfeaturesintheprocess:nichrome(NiCr)resistorsforprecisionandbulkforhighvalueresistors,highvalueMetal–Insulator–Metal(MIM)capacitors,1localand2thickglobalmetallayers[8].3.2DesignoftheresonatorThedifferencebetweentheoriginalinverseclassEinFig.2andthefinaltunedtopologyusedinourdesign,showninFig.3,isthelocationofblockingcapacitorCs.TheoriginalplacinginFig.2providestheDC-blockingtotwodirections:totheoutput(load)and,moreimportant,itblocksthedirectDC-currentpaththroughLptoourcasetheblockingcapacitorisunderneaththeresonatingcircuitasshowninFig.3,wheretheCsobstructstheflowofDC-currentthroughLptoground,butnottotheoutput(load).Thereisadirectwayforfundamentalcurrenttoflowtotheoutput,withoutpassinganyblockingcapacitor.TheDCblockingcapacitorcannowbemadesignificantlysmaller.Inourcasethereductionwasfrom100pFtolessthan50pF,whichmeanssavingsinchipareaandasasecondaryeffect,theabilitytotuneastabilizingtraptowantedfrequency(moreinchapter3.2)whilemaintaininggoodamplifierperformance.ThedesignoftheDC-blockisnowalsoslightlyeasier,sincepeakcurrentflowingintotheblockingbranchissmaller.Furthermore,theESRbetweendrainandloadissmaller.ThefundamentalcurrentamplitudesinponentsCsandLwere1.2and2A,respectively.ThetotalpeakcurrentsintheparallelresonatorstructurecanbeseeninFig.3.ThetraditionalinverseclassEdimensioning[4]for1.6GHzandPout=3Wresultsinlargechiparea,asduetohighQ=10thecapacitorCtotislarge(63.5pF)and—duetohighpeakcurrents(ca.6A)—theinductorgetsphysicallyhuge.Togetreasonableon-chipponentvaluesthedesignwasgraduallydeviatedfromthedesignprocedurein[4]byshiftingittowardslowerloadresistanceandQvalue,andincreasingtheresonancefrequency.Thisendedupinadimensioningthatprovidesclean,nonoverlappingcurrentandvoltagepulses,reasonablesizepassives,butwhichiseventuallyclosertoclassC–Efundamentalload[9]thantooriginalinverseclassE.Thefinalponentvaluesofthesimulationwithdiscreteponentmodelsandanoff-chiplow-passimpedancematchingnetworkto50Ωresultedinthefollowingdimensioning:resistiveload4Ω,Ctot=30pF,Lp=0:22nH,andLsosmallitcouldbeomittedfromthefinalcouldbereduceddownto50pFwithoutaffectingtheoverallperformance,anditcanbeusedtotuneastabilizingbelowthe-carriernotch,asshownlaterinFig.8.Theoverallsimulationresultswithalargeswitchingtransistor(12paralleltransistorswith18×50μm/0.5μmfingers)estimated5.6Woutputpowerwith72%drainefficiency.Thechallengewasnowtomaintainasgoodoutputpowerandefficiencywhilereplacingtheidealcircuitponentswithprocessdesignkit(PDK)ponentsandwhileaddingsomestabilizingcircuitstothedesignproblemcamewiththephysicaldesignoftheinductor.DespitetheloweredQvaluethecurrentamplitudewasstillsohigh(4.2Apeak)thatca.200lmwidemetallinewasneededfortheinductor,andtokeepthecenterofthe3/4-turninductoropenitcouldnotbemadephysicallysmallerthan0.4nH.Hence,thecapacitanceCtotandQvaluewerefurtherreducedabit,andtoreduceresistivelossesthecapacitanceCtotwassplitinto12parallelhigh-Qcapacitors.Thedrawnlayoutoftheresonatorstructurewasimportedinto2.5Dfieldsimulator,andS-parametersweresimulatedandparedwiththoseofthediscretesimulationprototype.TheunloadedphaseandmagnitudeoftheimpedancedataforparisonsfromS-parametersimulationsareshowninFigs.4and5.Thephaseandmagnitudedataofadistributedresonatorismarkedwithadashedlineinbothfigures.Thephasesandmagnitudesoftheresonatorsfollowalmostthesamethepleteamplifierwassimulated,thedrainefficiencywasabout70%andoutputpowerwasabout3.4W.Thereductioninoutputpowermaybeexplainedbyparasiticresistancesandbytheadditionofstabilizingcircuits.ThedrainefficiencyissurprisinglygooddespitethesomewhatloweredQandempiricaloutputcircuitsimulatedandimplementeddistributedresonatorisshowninFig.6.3.3StabilizingtheamplifierTheamplifiershowedatendencyofinstabilityduringlarge-signalS-parameter(LSSP)simulations.Intheend,stabilityhadtobeevaluatedthroughLSSP-basedstabilitycirclessinceunconditionalstability(K>1)couldnotbeachievedwithoutheavylosses.Stabilitycirclesweredrawnthroughoutafrequencyrangeof0.5–5GHz.Afterseveralsimulations,avarietyofstabilizingcircuitshadtobeusedtopensateringingthediscretecapacitorCswastunedto50pFtogenerateatrapintheoutputresonatoratabout1.2GHzfrequency.ThishelpedinachievingstabilityatfrequenciesbelowthefrequencybandasshownbyRollett’sK-factorinFig.7.The50pFvaluewaschosenforbothsmalldegradationinoutputpowerandforgoodstabilityperformance.TheeffectoftuningofthecapacitorCsisshowninFig.8,wherethecapacitoristunedfrom30to70pF.Further,5ΩofseriesresistancewasaddedtothreegatelinesasshowninFig.9(b)tokeeptheamplifierstablewithoutputstandingwaveratio(SWR)rangeof4.6:1.Also,awidebandRC-sinkcircuitwasincludedintheinputoftheamplifiertoreducethegaininhigherstableoutputSWRrangeincreasedwiththeRCfilterto22.6:1.Accordingtothesimulationstheseriesresistancescausedabout0.46dBgainlossandtheRCfilteragainanadditional0.67dB.Iftheamplifierhadtobeunconditionallystable(K>1),inthefrequencyrangeof0.1GHzto8.0GHz,theincreaseofseriesresistancesto9Ωwouldcauseanadditional0.40dBgainlossandmoreattenuationtothedrivesignal.Thetotaldecreaseofgainduetostabilizationwouldthenbe1.53dB,frommaximumgainof11.36–9.83dB.Intheimplementedform,themaximumsimulatedgainis10.23dB.3.4InputsignaltiminginaphysicallylargetransistorDuringsimulationstherewasanoticeablephaseshiftbetweenextremefingersofthewidetransistorconsistingof12918transistorswithawidthof50lmeach.Thisphaseshiftcausedpartialoverlapbetweenoutputpulsesanddecreasedthedrainefficiency.Atthattimetheinputnetworkwasmadeofaladder-likestructureshownasanexampleinFig.9(a).ThedistanceofthelinebetweenFETAandFETBiscloseto1mm,whichasapurelinedelaywouldresultinabout20psofdelay.Butthedelaydifferencewasmorethan80psandalsothepulsewidthoftheinputsignalwaslargerthanpredicted.Sincethetransistorsdonotswitchsimultaneously,theystarttoloadeachotherandconsumemorepower.Thereasonforincreaseddelayandwidenedpulsewidthisthesignaldependentgatecapacitancethatcausesconsiderableamountofsecondharmonicdistortionintheunterminatedladder-likeinputnetworkinFig.9(a).wherethesignalpathsarealmostequalinimprovedthetimingbehaviourandtheinputwaveformphasinginthesimulationswasnearlythesame.Onlythepulsewidthwasstillsomewhatlarge.Theequalinputroutingincreasedthedrainefficiencyoftheamplifierfrom55to68%.Theeffectsofgatecapacitancetogetherwithadditionalsolutionstotimingproblemshavebeenpublishedin[10].4FinalcircuitTheamplifierdiesized1.96mm×3.62mm(W×L)wasglueddirectlytoa6mmthickaluminiumheatsink.Thegold-platedprintedcircuitboard(PCB)containingoutputmatchingnetworkandsomeofthegatebiasingnetworkwasmountedontotheheatsink.NextthechipwaswirebondedandSMAconnectorswereaddedtothecircuit.ThefinalcircuitschematicisshowninFig.10,wherethedashedlineisusedtoseparatetheon-andoff-chipponents.LowerleftsideinthefigureisanLC-matchingnetworkwhichisfollowedbyanRC-sinkcircuit.TheRC-circuitincreasesthestabilityoftheamplifierbyprovidingawidebandloadingathigherfrequencies.Inthegatebiascircuit,upwardsfromthematchingcircuitistheparallelRLC-circuitthatisahighimpedanceattheoperatingfrequencywhiletheoff-chipparallelRC-circuitprovidesadditionalbiasresistanceinthelowfrequencies,thusincreasingthestabilityoftheamplifier.Ontherightsideofthetransistor,thetunedoutputresonatortogetherwiththeoff-chipmatchingcircuitisshown.Drainsupplyvoltageisdirectedthroughalongtransmissionlinethatisahighimpedanceattheoperationfrequency.TheparallelgateRCbiascircuitandoutputmatchingcircuitwereimplementedonthePCB,whichsimplifiedtheimplementedchipshowninFig.11.Upperleftbox(a)istheLCinputmatching,lowerleftbox(b)istheRLCbiasnetworkandontherightofthebiasisthebox(c)containingtheRC-sinkcircuit.Theequallengthinputlinesareshowninthebox(d),wheretheaddedseriesresistors(5Ωeach)showaswidesectionsinbetweentheequallengthlines.Thetransistorsetisshowninbox(e)anditconsistsof12transistorseachofwhichcontain18fingerswithawidthof50lmeach.Thesaturationcurrentofthetransistorisabout4A.Ontherightfromthetransistorsetthereistheoutputpathtogetherwiththeparallelresonatorinthebox(f).Bondingpadsarebelow(Gatebias),ontheleft(RFin)andup(RFoutanddrainbias).Twoorthreebondwiresareusedtominimizeseriesresistanceandinductanceandalsotomaximizecurrentcapabilityofthewires.4.1TheimplementedamplifierTheimplementedamplifierisshowninFig.12togetherwithapictureofthechiplayout.Theresonatorstructureontherightsideofthelayoutisclearlyvisibleintheactualchip.ThePCBhadtobedrilledopenandthealuminiumbaseplatemachinedforlevellingthechipalongthePCBsurface.Thiswaythebondwiresarekeptasshortaspossible.ThePCBcontainstheimpedancetransformingnetworkrequiredbytheoutputoftheamplifier.Further,thesupplyisprovidedthroughlonglinethathasrelativelyhighimpedanceatthefundamentalandhaslowresistanceatDC.ApartofthegatebiasingnetworkisalsolocatedinthePCB.ThetotalsizeofthePCBis17.1mm×37.6mm(Width9Length).5Measuredperformance5.1MeasurementsetupsAsingletonemeasurementwasusedtomeasuretheamplifieroutputpowerandefficiency.AnIFR2025signalgeneratorandabufferamplifierfromMini-Circuitsprovidedthedrivesignallevelof25dBm.TheoutputwasmeasuredwithaRohde&SchwarzZVA8vectorspectrumanalyser(VSA).TheloadpullmeasurementswereperformedwithFocusMicrowavesMPT1820tunersthatwereappliedbothtotheinputandoutputoftheamplifier.AsasourcewasRohde&SchwarzSMU200Awithabufferamplifier.Theinputpowerlevelswerefrom15to25dBm.TheRFinputandoutputpowersweremeasuredwithAnritsuML2438Apowermeterwithdualinput.TheharmoniccontentofthespectrumandoscillationspikesweremeasuredwithRohde&SchwarzFSQ40VSA.5.2TuningoftheamplifierInthefirstmeasurementstheamplifierdidnotmeetthesimulatedresponse.Measurementsgaveonly0.96Wofoutputpowerat1575MHzwhenthesimulatedfigureswere3.4Wofoutputpoweranddrainefficiencyof70%,allatsupplyvoltageof5.5V.Oursuspiciondirectedtowardsascribelinethatpassedveryclosetotheoutputresonatorstructureandpossiblycouldcoupletheoutputtotheinputoftheamplifier.ThescribelinewascutwithanUV-laserbutthishadnoeffecttothefrequencymeasuredDCcurrentoftheamplifierwasconsiderablyhigherthansimulated,suggestingthattheloadimpedanceoftheswitchingstagewastoolow.Theimpedanceseenatthedrainwasincreasedbyreplacingapairof2.7pFhigh-Qceramiccapacitors(AmplifierA,inTable1)intheexternaloutputmatchingnetworkwithone2.9pFcapacitor(AmplifierB,inTable1).Thismodificationincreasedtheoutputpowerto2Wandthedrainefficiencyto56%atthefrequencyof1625MHz.Theoutputpowerandefficiencyinthefrequencyrangeof1.5–1.7GHzisshowninFig.13.Theoutputpowerismaintainedwithin0.53dBinthedesiredfrequencyrange(1626.5–1660.5MHz)asshowninFig.13.Withinthatsamefrequencybandthedrainefficiencystaysabove53%whilethehighestefficiency,56%,isachievedat1626MHz.Byadjustingthesupplyvoltagetheefficiencyoftheamplifiercanbeincreasedevenmore,whichcanbeseenfromFig.14.Drainefficiencyincreasessteadilywhensupplyislowered.Atasupplyvoltageof2.5Vandfrequencyof1625MHz,theamplifierhasadrainefficiencyof65%.Thisimpliesthattheamplifiercanmaintainanefficientoperationalsowhenusedinanenvelopeeliminationandrestoration(EER)system.ThehighpeaksinatlowestsupplyvoltagesinFig.14arecausedbydrivesignalfeedthroughthatsumsintotheoutputsignal.5.3LoadpullmeasurementsMeasurementswereperformedwithloadpullsystemat1.6GHzspotfrequencytoseveralmodifiedamplifiers.ThedifferencesbetweentheamplifiersareshowninTable1.InthenextchapterswewillmainlyconcentrateonamplifiersCandDforreasonsthatwillbeapparentlateron.LetusnowdiscusstheamplifierCwhichisverysimilartoamplifierBmeasuredearlier.TunersoftheloadpullsystemwereconnectedtotheoutputsandinputsoftheamplifierC.Theloadtuningoffundamental,secondharmonicandthirdharmonicresultedinabout2.4Wofoutputpower(33.8dBm)whilemaintainingabout57.4%drainefficiencyatthispeakpowerspot.ThefundamentalloadimpedanceintermsofpowerwasatslightlyhigherimpedancethantheoptimumdrainefficiencypointasshowninFig.15,wherethe-1dBoutputpowerpoints(triangles)and-5%unitefficiencypoints(circles)areshown.Thepeakefficiencypointinthefigureis(a)(58.6%)andpeakpoweris(b)(33.9dBm).Theoptimumefficiencyareaisratherlarge.Bothoftheloadharmonicswereevenmorerelaxed,anddifferencesforexampleinoutputpowerhadtobemeasuredintenthsofdecibelsratherthanindecibels.Further,theefficiencydifferencesweremeasuredinoneortwopercentageunitsinsteadoffivetoten.Asanexample,thethirdharmonicoptimumoutputpointswithin0.2dBfrommaximum(triangles)andefficiencypointswithin2%unitsfrommaximum(circles)areshowninFig.16.Asitcanbeseen,thethirdharmonicimpedanceisnotascriticalasthefundamentaltone.Theoptimumefficiencyismarkedwith(a)andmaximumoutputpowerismarkedwith(b).Itshouldbenotedthattheadjustmentofthethirdharmonicdidnotincreaseoutputpowerontheabsolutescalenorthedrainefficiency.Thepeakoutputpowervalueremainedwithin0.2dBofthepeakvalueofthefundamentalloadpullandthedrainefficiencyrosefrom58.6onlyto59.8%shownattheSmithchartpoint(a)inFig.16.Theinsensitivityoftheamplifiertoharmonictuningiscausedbythelongdrainbiaslinethatislowimpedanceatthesecondharmonicandthelowpassmatchingnetworkattheoutputthatattenuatesthethirdharmonic.5.4SourcepullmeasurementsThesourcepullofthefundamentalimpedancedidincreasetheoutputpowerandefficiencyofamplifierCslightly.Theoptimumdrainefficiency(circles)andoutputpowerpoints(triangles)(a)and(b),respectively,areshownFig.17.Thepowerpointsarewithinthelimitsof0.2dBandefficiencywithinadifferenceof2%units.Theamplifierefficiencyrosewiththefundamentalsourcetuningto62.1%(pointa)andtheoutputtoabout2.5W(34.1dBm,pointb).Harmonicsourcepullmeasurementsshowedthattheharmonicimpedanceswerenotascriticalasthefundamental.ThisisduetothelowpassinputmatchingandthewidebandRC-sinkcircuit.TheRC-sinkcircuitlowersthecalculatedmagnitudeoftheimpedanceespeciallyathighfrequencies,asshowninFig.18(b).Thishasaneffecttobothsecondandthirdharmonicimpedances.ThemagnitudeoftheimpedancewithouttheRC-sinkisshownasareferenceinFig.18(a).Inbothcasestheinputmatchingcircuitswerenotincludedinthecalculations.5.5StabilityoftheamplifierAtfirsttheamplifierAdidshowsomeunstablebehaviourduetosupplyvoltagemodulationcausedbyinsufficientbiasdecouplingatthedrain.Theinstabilityappearedatlowinputpowerlevelsasnoisesidebandsthatliedonbothsidesoffundamentalfrequency.Wheninputpowerwasloweredfurtheron,theamplifierdidbreakintofullscaleoscillation.Asacure,thesupplyimpedancewasloweredbyalargenumberofdecouplingcapacitors(4×470pF)addedtothedrain.InanEERapplication,thesupplymodulatorwillprovidelowenoughimpedanceatthedrain.WhentheloadpullwasdonetotheamplifiersA,CandD,aspuriousoscillationdetectionwasappliedatalevelof-50dBc.Withthissetupwewereabletoparethesensitivityofdifferentamplifierstooscillations.WefoundoutthattheRC-sinkcircuitusedinamplifiersAandCindeedimprovedstability,especiallyinthelowinputpowerlevels.DatausedforparisonwasmeasuredfromamplifierD,wheretheRC-sinkwascutusinganultravioletlaser.Theoscillationpointsofthefundamentalimpedanceloadpullwithalow15dBminputpowerareshowninFig.19.Theoscillationsidebandsdetectedare1701and1489MHz.IfweparethisresulttoamplifierA,theamountoffoundoscillationpointsisconsiderablysmallerandthelocationofthemisrathertightlyspacedinthelowimpedancearea,asshowninFig.20.Theoscillationfrequencyinthiscaseis1568MHz.TheamplifierAandamplifierDhadadifferentfrequencyforthemodulatingspuriousponents:Withoutthedampingcircuitthemodulatingspuriouswasca.±100MHz,whilewiththedamperthemodulationappearedatabout±30MHz.TheprobablereasonforthisliesindifferentdrainbypassingastheamplifierDhadlesssupplycapacitance(4×470pFless).Theeffectofthiswasstudiedbysimulatingfrominputtoloadtransmission(S21)inthedrainbiasandmatchingnetwork.ThecircuitfromamplifierDshowsresonanceataround93MHzasshowninFig.21(a),whileintheamplifierAthedrainresonanceisat27MHzfrequencyasshowninFig.21(b).Asareference,ameasuredspectrumofamplifierA’soutputisshowninFig.22,wherethemarkersoneandfourareat±33MHzdistancefromthefundamentalfrequency.Theinputpowerinthiscaseis15dBmandfundamentalloadimpedanceisatoneofthefoundoscillationimpedances(Г=0.370,?=165.3).Theincreaseofchipdecouplingcapacitors(4×470pF)inthecaseofamplifierAdidlowertheresonancefromaround100MHzinto30MHzregion.Insidethe±30MHzbandtherearealsootheroscillationtoneswhichresembleaquasi-periodicsolutionandachaosspectrumofquasi-periodicandchaosspectrumsareshownforexamplein[11].Aninterestingpointoftheresonanceseenwasthatthelargeelectrolyticcapacitorsappliedtothebiassupplydidnotattenuatetheabout30MHzresonance,duetoitshighinductance.5.6AdditionalfindingsSwitchingamplifiersaredependentonsufficientamountofgatedrive,andvariationsinthedrivesignalaffectquicklytheperformanceoftheamplifier.Inourcasesmallvariationsintransistorpinch-offvoltageresultedin2–3dBdifferencesingainbetweentheamplifierswhenbiasvoltagewaskeptconstant.Suchcleardifferencescouldbeseeninvectornetworkanalysermeasurementswitha0dBminputdrive.Moreconstantresultscouldbederivedbyadjustingthesmalldrainbiascurrentstoequalwhennodrivesignalwasapplied.Nowthemeasurementsofgainwerematchedwithin0.8dB.6SummaryAtunedRFpoweramplifierhasbeendesignedforoperationinafrequencybandof1.6–1.7GHz.Theamplifierwasdesignedempiricallytohavenon-overlappingdrainvoltageandcurrentpulses,andtherequiredresonantcircuitwasimplementedon-chip.AnewpositionoftheDC-blockingcapacitorgeneretedaresonatortrapthatstabilizestheamplifierbelowthedesiredband,andagateRC-sinkcircuitwasusedtostabilizetheamplifierathigherfrequencies.Further,equallengthinputlineswereimplementedtoequalizethetimingofgatesignals.ThestabilityoftheamplifierwasevaluatedthroughsimulationsoflargesignalS-parametersandstabilitycircles.AdditionalresistancestogetherwithanRC-sinkcircuithadtobeappliedtokeepthestableoutputSWRrangeatmorethan22.6:1.TheamplifierwasimplementedontoaGaAssubstratewithdepletionmodehighelectronmobilitytransistors(FETs).Theimplementedamplifierdelivers2Wofoutputpowerwhilemaintaining56%drainefficiency.Thefrequencyresponseiswithin0.53dBatafrequencybandof1626.5–1660.5MHzwhilethedrainefficiencystaysabove53%inthisdesiredband.Theamplifierwasalsomeasuredwithaloadpullsystemataspotfrequencyof1.6GHz.Withthehelpoftunerstheamplifierachievedabout2.5Wofoutputpowerand62%efficiency.Loadpullalsorevealedtheamplifier’ssensitivitytooscillationsatsmalldrivelevels.Itwasfoundoutthattheoutputmatchingnetworkhasalow-frequencyresonancethatmightcontributetotheunstableimplementedgatesinkwasverifiedtostabilizethecircuit.ItmightbeabeneficialideatodesignaninputLC-trapcircuittunedtothesecondharmonic,sincethereissecondharmoniccontentattheinputwhichwidenstheinputwaveforminthetimedomain,creatingproblemsintermsofefficiencyandpower.Further,increasingthethirdharmoniccontentcouldmaketheinputwaveformmoresquare-likewhichisadesiredfeatureinswitchingamplifiers.Acknowledgements：ThisworkhasbeensupportedbyTheAcademyofFinland,InfotechOuluGraduateSchool,TriQuintSemiconductorInc.,NokiaFoundation,TaunoTonningFoundation,UllaTuominenFoundationandThefoundationofRiittaandJormaJ.Takanen.MyspecialthankstothepersonneloftheDepartmentofElectronicsandTelemunicationsintheNorwegianUniversityofScienceandTechnology(NTNU)andtothepersonneloftheMicro-andNanotechnologyCentreintheUniversityofOulu.References1.Cripps,S.C.(2006).RFpoweramplifiersforwirelessmunications(2edn).685CantonStreet,Norwood,MA02062:ArtechHouseInc.2.Raab,F.(1977).IdealizedoperationoftheclassetunedpowerandSystems,IEEETransactionson,24(12),725–735.3.Sokal,N.O.,&Sokal,A.D.(1975).Classe–anewclassofhighefficiencytunedsingle-endedswitchingpowerJournalofSolid-StateCircuits,10(3),168–176.4.Mury,T.,&Fusco,V.(2005).Series-l/parallel-tunedclass-epoweramplifieranalysis.InProc.Europeanmicrowaveconference(Vol.1,p.4).doi:10.1109/EUMC.2005..5.Tayrani,R.(2007).Aspectrallypure5.0w,highpae,(6–12ghz)ganmonolithicclassepoweramplifierforadvancedt/rProc.IEEEradiofrequencyintegratedcircuits(RFIC)symposium(pp.581–584).doi:10.1109/RFIC.2007.380951.6.Hietakangas,S.,Rautio,T.,&Rahkonen,T.(2006).1ghzclasserfpoweramplifierforapolartransmitter.InProc.24thnorchipconference(pp.5–9).doi:10.1109/NORCHP.2006.329232.7.Hietakangas,S.,Rautio,T.,&Rahkonen,T.(2008).OneghzclasserfpoweramplifierforapolarIntegratedCircuitsandSignalProcessing,AnInternationalJournal,54(2),85–94.doi:10.1007/s10470-007-9109-x.8.TriquintSemiconductorInc.(2007).TQPED0.5umE/DpHEMTfoundryservice(2.2edn).foundryTQPEDv2_2.pdf.9.Kazimierczuk,M.,&Tabisz,W.(1989).Classc-ehigh-efficiencytunedpoweramplifier.CircuitsandSystems,IEEETransactionson,36(3),421–428.doi:10.1109/31.17589.10.Hietakangas,S.,Typpo,J.,&Rahkonen,T.(2008).Effectsofinputroutinginswitchedrfamplifiers.InProc.workshoponintegratednonlinearmicrowaveandmillimetre-wavecircuitsINMMIC2008(pp.35–38).doi:10.1109/INMMIC.2008..11.Suarez,A.,Jeon,S.,&Rutledge,D.(2006).Stabilityanalysisandstabilizationofpoweramplifiers.IEEEMicrowaveMagazine,7(5),51–65.doi:10.1109/MW-M.2006.247915.SimoHietakangaswasborninAlaha¨rma¨,Finland,in1980.HereceivedtheM.Sc.degreeinElectricalEngineeringfromtheUniversityofOulu,Oulu,Finland,in2005,andiscurrentlyworkingtowardthePh.D.degreeattheUniversityofOulu.HistechnicalinterestslieinthefieldofanalysisandmodelingofswitchingRFpoweramplifiers.JukkaTyppo¨wasborninOulu,Finland,in1963.HereceivedhisM.Sc.degreeinUniversityofOulu,in1992,andhisPh.D.degreeinNorwegianUniversityofScienceandTechnology,in2003.Currently,heworksasaresearchfellowatNorwegianUniversityofScienceandTechnology,DepartmentofElectronicsandTelemunications.HiscurrentresearchtopicisintegratedRFpoweramplifiers.TimoRahkonenwasborninJyva¨skyla¨,Finland,in1962.HereceivedtheDiplomaEngineer,Licentiate,andDoctorofTechnologydegreesfromtheUniversityofOulu,Oulu,Finland,in1986,1991,and1994,respectively.HeiscurrentlyaProfessorofcircuittheoryandcircuitdesignwiththeUniversityofOulu,whereheconductsresearchonlinearizationanderror-correctiontechniquesforRFpoweramplifiersandA/DandD/Aconverters.1.6GHZ，2W集成式調(diào)諧射頻式接收功率放大器的設計摘要：這篇論文是對一種指定運行在上行頻率為1626.5到1660.5MHZ范圍內(nèi)的國際海事衛(wèi)星集成調(diào)諧功率放大器的描述。這個放大器基本的拓撲結構在于并行優(yōu)化逆E類放大器，修改這類放大器是通過在一個新的位置安裝直流隔離電容并且通過調(diào)整電容的尺寸來提高低于預期波段頻率的穩(wěn)定性。另外，新的安放位置減少了排水和負載的損失。在電路中很高的電流使得使用寬電感寬度和在芯片上的諧振器的高Q值的手指電容很有必要。該放大器被實現(xiàn)為砷化鎵（GaAs電路（IC）的交付2W的輸出功率，而漏極效率為約56％。測量包括信號源和負載以達到進一步改善該放大器的性能，并在小輸入驅(qū)動電平進行時調(diào)查穩(wěn)定性。關鍵詞：逆E級，功率放大器，自激振蕩，偏置網(wǎng)絡1.介紹在今天的高功率通信系統(tǒng)傳統(tǒng)的線性放大器的可用性是由于其低效率而被限制。這個事實推動了向更高效的放大器的研究興趣，比如E級[1-3]和逆E級[4]。此外，較高的輸出功率的需求意味著更高的峰值電流和電壓在漏極或集電極電路。這將創(chuàng)建要求高的晶體管的兩個最大擊穿值和單片微波集成電路（MMIC）的無源電路。有限的導電性和有限的電容大小，以應付熱的效果可以通過仔細設計MMIC而達到最小化。另外，晶體管的新興技術似乎能承受更大的電流密度和峰值電壓[5]，因此，在設計高功率器件時，技術的選擇變得越來越重要。本文的目的是要顯示與開關高功率射頻（RFPA）具有集成輸出脈沖整形的設計經(jīng)驗。在第二章中介紹的E級和逆E級操作是重新審視兩種拓撲結構之間的差異.第三章介紹了輸入和輸出電路，穩(wěn)定的電路的設計，并提供一些提示關于在一個多指晶體管的輸入端減少時差的方式。第四章給出了最終的原理和實現(xiàn)芯片的照片。在第五章中，實測性能是通過使用兩個基本的單音測量設備和現(xiàn)代化的負載拉移系統(tǒng)采用多功能調(diào)諧器（MPT）進行的報告。最后一個部分提供的有關穩(wěn)定電路的問題的文章和討論的摘要。2.E級與反E級放大器E級和逆E級被視為開關放大器。理想情況下，在兩者的晶體管被驅(qū)動打開或關閉，該開關動作產(chǎn)生一系列電壓和電流脈沖的輸出。這些脈沖相移，因此不會彼此重疊。理想的非重疊將導致晶體管具有100％的漏極效率操作。經(jīng)典E類DC1極電流的波形，虛線是歸一化的漏極電壓。在E類為最佳操作的要求是零電壓開ZVSE類的波形已經(jīng)交換了位置，以便在圖1中的實線波形是漏極電壓，虛線是漏電流。最佳的操作也被改變到零電流開關（ZCSE級相對于經(jīng)典實現(xiàn)的優(yōu)點是漏極峰值電壓比傳統(tǒng)的E級較低，在輸出電路中的電感值較小，它可以在一個MMIC芯片實現(xiàn)，節(jié)省面積，并且通?？梢缘玫礁〉碾娖鞔?lián)電阻（ESR[4]。此外，為了接收串聯(lián)