电子科学与技术外文翻译

电子科学与技术外文翻译班级：学号：姓名：指导教师：时间：Designofintegrated1.6GHz,2WtunedRFpoweramplifierAbstract：ThispaperdescribesthedesignofanintegratedtunedpoweramplifierspecifiedtooperateatInmarsatsatelliteuplinkfrequenciesfrom1626.5to1660.5MHz.ThebasictopologyoftheamplifierliesontheparalleltunedinverseclassEamplifierthatismodifiedbyplacingtheDC-blockingcapacitorintoanewpositionandbyadjustingthesizeofthecapacitortoimprovestabilitybelowthedesiredband.Further,thenewpositioningreduceslossesbetweendrainandload.Thehighcurrentsflowinginthecircuitmadeitnecessarytousewideinductorwidthandhigh-Qfingercapacitorsintheon-chipresonator.TheamplifierwasimplementedasaGalliumArsenide(GaAs)integratedcircuit(IC)thatdelivered2Wofoutputpowerwhilethedrainefficiencywasca.56%.Measurementsincludedsourceandloadpullstofurtherimprovetheperformanceoftheamplifierandtoinvestigatethestabilityatsmallinputdrivelevels.Keywords:InverseclassE•Poweramplifier.Self-oscillation•Biasnetwork1IntroductionTheusabilityoftraditionallinearamplifiersintoday’shighpowercommunicationssystemsislimitedduetotheirlowefficiency.ThisfacthasdriventheinterestofresearchtowardsmoreefficientamplifierssuchasclassE[1–3]andinverseclassE[4].Also,thedemandofhigheroutputpowermeanshigherpeakcurrentsandvoltagesinthedrainorcollectorcircuits.Thiscreateshighrequirementsforbothmaximumbreakdownvaluesofthetransistorandtothepassivecircuitryofthemonolithicmicrowaveintegratedcircuit(MMIC).TheeffectoflimitedconductivityandlimitedcapabilitytocopewithheatcanbeminimizedthroughcarefuldesignofMMIC.Further,emergingtransistortechnologiesseemtowithstandlargercurrentdensitiesandpeakvoltages[5],andtherefore,thechoiceoftechnologyisincreasinglyimportantwhendesigninghighpowerdevices.Theaimofthispaperistoshowexperiencesrelatedtothedesignofswitchinghighpowerradiofrequency(RF)amplifiers(PA)withintegratedoutputpulseshaping.InthesecondchaptertheintroductiontoclassEandinverseclassEoperationisrevisitedandthedifferencesbetweenthetwotopologiesarereviewed.Thethirdchapterdescribesthedesignoftheinputandoutputcircuitry,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,thepossibilitytoaccommondateseriesinductanceasapartofresonatingcircuitryisuseful,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-currentpaththroughLptoground.In