Proceedingsofthe36thEuropeanMicrowaveConferenceHighEfficiencyLDMOSCurrentModeClass-DPoweramplifierat1GHzHosseinMashadNemati,ChristianFager,HerbertZirathChalmersUniversityofTechnology,DepartmentofMicrotechnologyandNanoscience(MC2),MicrowaveElectronicsLaboratory,Sweden,Phone:+46-(O)-31-7725048,E-mail:mashad@chalmers.seAhighpower,highefficiencycurrentmodeAbstractclass-D(CMCD)poweramplifier(PA)isdesigned,implemented,andcharacterizedbasedonLDMOStransistors.Adrainefficiencyof71%wasachievedwithanoutputpowerof20.3Wandagainof15.1dBat1GHz.Toourknowledge,thisresultrepresentsthehighestefficiencyfortheCMCDPAsbasedonLDMOSandthehighestgainforallswitchingmodePAsthathavebeenreportedforhighpowerapplications(outputpowerofmorethan7W),atfrequenciesabove800MHz.Moreover,awide-bandlumped-componentbalunhasbeenusedfortheCMCDPAwhichenablessignificantsizereductionofthisclassofPAforL-bandapplications.IndexTermsSwitchingmodepoweramplifiers,currentmodeclass-D,LDMOSrequirementofclass-Eandtheoutputcapacitanceofthedevice[8].However,CMCDandclass-F-1donotsufferfromsuchalimitation.InaCMCDPA,theoutputcapacitancecanbeeasilyabsorbedintheoutputnetworkcapacitor.CMCDPAcanofferhigherbandwidthcomparingtotheotherSMPAs,providingthatwidebandinputimpedancematchingisemployed[3].Underidealizedoperation,class-F,D,andtheirinversecounterpartspresentthehighestoutputpowercapability(Pmax)forSMPAswhichis0.159(comparewith0.098forclass-E).PreviouslypublishedresultsfordifferentSMPAswithoutputpowerofmorethan7Watfrequencieshigherthan800MHzaresummarizedinTableI.Accordingtothistable,CMCDPAhasachievedthemaximumgaincomparingtotheI.INTRODUCTIONotherclasseswhilethedrainefficiencyisstilllowandaroundPoweramplifier(PA)isakeybuildingblockofany60%.TABLEIcommunicationsystem.ThemainpurposeofaPAistoRECENTPUBLISHEDACHIEVEMENTSconverttheDCsupplypowertoRFpowerthatisfedtotheantenna.Thereareanumberoffigureofmerits(FOMs),byGainAuthorClassfPoutI/whichthePAperformanceisevaluated.Themostimportant(GHz)(%)(W)(dB)FOMsarelinearity,efficiency,outputpower,andgain.F.LepineF'177.812.412.9Highefficiencyisimportantforallapplications,whether[10]portableorfixed.Infixedapplicationssuchasbasestations,F.LepineF'1.8106013whereveryhighoutputpowerisrequired,highefficiency[10]reduceselectricityexpensesandcoolingsystemrequirementsA.AdahlE1737.910whichbothmakethetotalsystemmorecost-effective.[11]Moreover,whenasystemisunderlessthermalstress,whichW.N.Edelstein0.8603010E/Fisachievedbyhighefficiency,itwillbemorereliable.[12]Inswitchingmodepoweramplifiers(SMPAs),wheretheF.Wang111.17060E/Factivedeviceisusedasaswitch,atheoreticalefficiencyof[13]100%isachieved.Inpractice,thedeviceparasiticsandA.Long1146013CMCDlimitedswitchingspeeddegradestheefficiencyofSMPAs.Athighfrequencies,thelossesduetothereactiveparasiticsK.Ji-YeonCMCD1.8635010ofthedevicebecomemoresignificant.Capacitivedischarge[14]lossesofthetransistoroutputcapacitanceandinductiveH.M.Nemati171CMCD20.315.1lossesofthetransistoroutputinductancecanbeavoidedifThispaperzerovoltageswitching(ZVS)andzerocurrentswitching(ZCS)areprovided,respectively.However,ZVSisofmoreimportanceathighfrequencies[3].ThisimpliesthattheII.CMCDPAPRINCIPLEOFOPERATIONSMPAswhichprovideZVSaremoresuitabletoachievehighefficiencyathighfrequencies.Thisconditionismetinclass-ThebasictopologyofaCMCDPAisshowninfig.1.TheE[1],CMCD[3],F-1[2],DE[4],andE/F[7].topologyconsistsoftwotransistors,anRLCparallelresonantForacertaindeviceandoutputpowerlevel,thefrequencycircuitatthefundamentalfrequency,andRFchokes(RFCs).ofclass-EPAislimited;duetotheoptimumcapacitorTheinputdriveforthetwotransistors(TI,T2)shouldbeof2-9600551-6-0(D2006EuMA176September2006,ManchesterUKequalamplitudewith1800phasedifference.Thisimpliesthatabalun(balancedtounbalancedconverter)isrequiredfortheinputnetwork.Anotherbalunisalsorequiredattheoutputtoprovidethebalancedload.+VDD+VDD-IuuFig.1.CMCDtopologyThedrainvoltageandcurrentwaveformsinanidealCMCDPAareshowninFig.2.Thedrainvoltages(Vdl,Vd2)arehalf-sinusoidal,consistingofaDCcomponent,fundamentalfrequencycomponent,andevenharmoniccomponents[5].Thedraincurrents(Id,,Id2)aresquarewave,consistingofaDCcomponent,fundamentalfrequencycomponent,andoddharmoniccomponents[5].TheRLCtankprovidesashortcircuitforalloddharmonicsofthecurrentandthebalancedstructureprovidesanopencircuitforallevenharmonicsofthevoltage.Vdharmonics,thebalunmayalsodisturbtheharmonicterminationconditions.AnidealbalunforaCMCDPAshouldprovideanopencircuitconditionforallevenharmonics(oratleastthesecondharmonic).TheshortcircuitconditionwhichisprovidedbythetankLCshouldnotbedisturbedbythebalunfortheoddharmonics.Realizingawidebandbalun(uptoatleastthethirdharmonic)isverydifficultforfrequenciesbeyondabout500MHz[8].Inpractice;thebaluns,notonlydegradetheCMCDPAperformance,butalsomakethePAmorespace-consuming(especiallyforfrequenciesofabout1GHz).Thedrain-sourcevoltage(VDS)ofatransistorisnotzerowhentheswitchisONwhichresultsinanadditionallossanddegradationinefficiency.Moreover,asaresultofthenon-zeroON-statevoltage,thepeakdrainvoltagebecomeslessthantheestimationsmadeintheidealcase(WVDD)[5],allowingtheuseofhigherdrainvoltageinthepracticaldesign.Notethat,thedrainpeakvoltageshouldbelessthanthedevicebreakdownvoltage(BV).Therefore,theoutputpoweroftheCMCDPAwhichisproportionaltothesquareofVDDislimitedbythedeviceBV.III.DESIGNANDIMPLEMENTATIONThe\"Root\"modeloftheLDMOStransistor,MRF282SR1,providedbyFreescaleisusedinAgilent'sADStoperformthedesignandsimulations(usingtheHarmonicBalancesimulator).ThesamedevicewasusedinotherSMPAs,designedandcharacterizedin[10]and[11]at1GHz.Thisenablesafaircomparisonbetweentheseclassesforhighpowerapplications.TheCMCDdesignschematicusedinthisworkisshowninFig.3.TTV21DCDD-----------r4He_4VGGVDDrr2rrwtrIwtFig.2.IdealizedCMCDdrainvoltageandcurrentwaveformsThewaveformsandharmonicterminationconditionsofCMCDaresimilartothoseofclass-Fl.TheonlydifferenceisinthewaythattheharmonicimpedanceconditionsaremetinthesetwoSMPAclasses.Inpractice,theharmoniccontentsofthewaveformsarelimitedduetotheintrinsicandextrinsicparasiticcomponentsofthedevice.Themaximallyflatapproximationmethod[6]isusedtoapproximatetheidealwaveformsbyafinitenumberofharmonics.Asthenumberofharmonicsincreases,theefficiencyisincreased.Withproperharmonicterminationforuptothethirdharmonic,75%drainefficiencycanbeachieved[6].InadditiontotheundesirableeffectofthedeviceparasiticcomponentsinlimitingthepresenceofthehighorderkLI--ARl1VGGVGGVD\\NarrowTlineas--1aninductorVDDL2Fig.3.CMCDdesignschematicThebroad-bandlumped-elementbalun(secondorderlatticebalun)presentedin[15]isusedinthisdesign.Thetotalsizeofthebalunis10x7mm.TheQvalueoftheRLCnetworkissetto10witha50Qload.Asshowninfig.3,adifferentialinputmatchingnetworkisusedwhichmakesthevaluesoftherequiredcapacitors(Cl,C2)lowerandavoidsanydifferenceinthetwoinputbrancheswhentheyarevariedinpracticefor177tuning.C1,C2,andC3(seefig.3andfig.4)areATClimitedgain,andcausethePAEtodecrease.Asshownincapacitors(600sseries).Theirvaluesare1.8,5.6,and2.7pF,fig.5,thereisadegradationofabout1dBinPoutfortherespectively.Thebaluncapacitorsarealsochosenfromthemeasurementresultsandtherefore,anabsolutereductionofsameseries.Insimulations,theyarereplacedbytheirseries8%inqisintroduced.Moreover,duetothehighgainoftheresonantcircuitmodel.AircoreinductorsfromCoilcraftCMCDPA,thevaluesofCandPAEareveryclose.(1005series)areusedinthedesignandtheirSpicemodelisFig.6showsthePAperformanceversusdrainvoltage.employedforthesimulations.Theinductor,intheoutputTheinputdrivewaschosentobe28dBmtoincreasethenetwork,isrealizedbyanarrowtransmissionlinebetweenoutputpowerlevelwhileC,gain,andthusPAEarestillhighthetwotransistors(seefig.3andfig.4).(seefig.5).Accordingtothesimulations,thepeakdrainvoltagewasbelowthedevicebreakdownvoltage(65V)forallVDDlessthan32V.Theoutputpower,aspredictedbytheOutputtheory,isproportionaltothesquareofVDDwhiletheefficiencyvariesslightly.ForVDD=30VandPi,=28dBm,anoutputpowerof20.3Wismeasuredwithq=71%.ThegainEofthePAis15.1dBinthiscase.0ThePAperformanceversusVGGisshowninfig.7.Asshowninthisfigure,byincreasingthegatebias,theoutputpowerincreasesslightlyduetotheincreaseintheONdurationofthedevicewhiletheefficiencyisreduced.TlineasFig.8showsthefrequencyperformanceofthePA.Adrain|lllk__Baluninductorefficiencyofmorethan50%isachievedoverabandwidthof90MHz(9%).Input.Narrow10.5cmFig.4.PictureoftheCMCDcircuitrealizationAtolerancestudywasperformedthroughMonteCarlosimulatorinADS,takingintoaccountthelumpedcomponenttolerances.ItwasfoundthatthelumpedcomponenttolerancescouldonlydegradethePAperformanceslightly.Moreover,Momentumsimulationwasperformedforasampleoftheoutputnetwork.GoodagreementwasfoundbetweentheresultsinschematicandMomentumsimulationsinADS.ThecircuitwasimplementedonDuroid5870witharelativedielectricconstantof2.33andathicknessof0.8mm.Thecapacitors(Cl,C2,andC3)werereplacedbyJohnsonvariablecapacitorsinordertobeabletotunethePAduringthemeasurements.Thesubstrate,passivecomponents,andtransistorsweremountedonaheatsinkinordertocoolthePA.ThepictureofthePAisshowninfig.4.ThesizeofthePAis8.5x10.5cm.Asshowninthefigure,thebalunsizeisverysmallcomparedtothetotalsizeofthePA(only0.800ofthePAlayoult).ThismeansthatthePAsizecanbereduicedsignificantlyusingthistypeofbalun,providingthatthecouplingeffectsarewellconsidered.IV.SIMULATIONANDMEASUREMENTRESULTS44A--PA-PoutssimulatePPout(measured)mee380,7nir-CL3422......24.....30ti202226283020.Pin(simulated)--3PAE-113(simulated)2(measured),B-IsnPAEr(measd0,3q28I,.I.,I.,,,,.I.,.10,22426283032Pin(dBEm)Fig.5.EfficiencyandoutputpowerversusinputpowerforVGG=2V,VDD=26V601Pousiinulated)Pout(measured)t~~~~~~~0.-^908Eco4506m35,.hg:10A--Inthispart,simulationresultsoftheoptimumdeignandthemeasurementresultsaftertuningarepresentedandcompared.Fig.5showsthesimulationandmeasurementresultswhentheinputpower(Pi,)isvaried.Forlowinputdrivelevels,theoutputpower(P0,,),drainefficiency(j),andpoweraddedefficiency(PAE)increaseastheinputpowerisincreased.However,P0,,andjsaturateforhigherPi,,duetothedevice30515n(measured)0i--o--PAE(sitnulated)E~PAE(measured)l:0,220253035DD(V)n(simulated)Fig.6.EfficiencyandoutputpowerversusdrainvoltageforVGG=2VandPin=28dBm1784542F.........Pout(simulated)Pout(measured)0.9projectsupportedbyEricssonAB,andChalmersUniversityofTechnology.m-394-OL--a--n08-REFERENCES[1]N.0.Sokal,A.D.Sokal,\"ClassE-Anewclassofhigh-efficiencytunedsingle-endedswitchingpoweramplifiers,\"IEEEJournalofSolid-StateCircuits,Volume10,no.3,Page(s):168-176,Jun.1975.[2]A.Grebennikov,RFandMicrowavePowerAmplifierDesign,USA:McGraw-HillPublishers,2005.[3]H.Kobayashi,J.M.Hinrichs,P.M.Asbeck,\"Current-modeclass-Dpoweramplifiersforhigh-efficiencyRFapplications,\"IEEETransactionsonMicrowaveTheoryandTechniques,Volume49,no.12,Page(s):2480-2485,Dec.2001.[4]H.Koizumi,T.Suetsugu,M.Fujii,K.Shinoda,S.Mori,andK.Iked,\"Class-DEHighEfficiencyTunedPowerAmplifier,\"IEEETransactionsonCircuitsandSystems,Volume43,no.1,Page(s):51-60,Jan.1996.[5]T.Dellsperger,\"DeviceEvaluationforCurrent-ModeClass-DRFPowerAmplifiers,\"DiplomaThesis,UniversityofCalifornia,SantaBarbara,2003.[6]F.H.Raab,\"Class-Fpoweramplifierswithmaximallyflatwaveforms,\"IEEETransactionsonMicrowaveTheoryandTechniques,Volume45,no.11,Page(s):2007-2012,Nov.1997.[7]S.D.Kee,I.Aoki,A.Hajimiri,D.Rutledge,\"Theclass-E/FfamilyofZVSswitchingamplifiers,\"IEEETransactionsonMicrowaveTheoryandTechniques,Volume51,no.6,Page(s):1677-1690,June2003.[8]D.Choi,\"Highefficiencyswitched-modepoweramplifiersforwirelesscommunications,\"Ph.D.Dissertation,UniversityofCalifornia,SantaBarbara,Mar.2001.0,7m...n(measured)-x-(simulated)PAE-PAE(measured).-(simulated)N3-050......0,63,50,51v1,522,53(V)Fig.7.EfficiencyandoutputpowerversusgatevoltageforVDD=30VandPin=28dBm0,8-0o.0.420,2-u.0mf(GHz)Fig.8.EfficiencyandoutputpowerversusinputfrequencyforVDD=3OV,VGG=2V,andPi,=28dBVI.CONCLUSIONInthispaper,aCMCDPAbasedonLDMOStransistorswasdesigned,fabricated,andmeasured.Goodagreementwasfoundbetweenthesimulationandmeasurementresults.Adrainefficiencyof710%wasachievedwithanoutputpowerof20.3Wandagainof15.1dBat1GHz.Thisresultrepresentsstate-of-the-artat1GHzforhighefficiency,highpowerCMCDPAsbasedonLDMOS.Moreover,thegainofthePAisthehighestcomparedtootherpublishedSMPAsforhighpowerapplicationsatL-band.Thepresentedresultsalsoprovethepossibilityofusingacompactwidebandlumped-componentbaluntoachievehighefficiencyperformance.Smallsizeofthistypeofbalun,enablessignificantreductionofthetotalsizeofthePAatfrequenciesofabout1GHz.[9]A.Long,Y.Jingshi,S.I.Long,\"A13WcurrentmodeclassDhighefficiency1GHzpoweramplifier,\"The200245thMidwestSymposiumonCircuitandSystems,Volume1,Page(s):1-33-6,2002.[10]F.Lepine,A.Adahl,H.Zirath,\"L-bandLDMOSpoweramplifiersbasedonaninverseclass-Farchitecture,\"IEEETransactionsonMicrowaveTheoryandTechniques,Volume53,no.6,Part2,Page(s):2007-2012,June2005.[11]A.Adahl,H.Zirath,\"An1GHzclassELDMOSpoweramplifier,\"33rdEuropeanMicrowaveConference,Volume1,Page(s):285-288,Oct.2003.[12]W.N.Edelstein,C.Andricos,A.Moussessian,F.Wang,andD.B.Rutledge,\"High-efficiencyL-bandtransmitter/receivermoduleforsyntheticapertureradar,\"IEEERadarConf,Page(s):238-243,May2003.[13]F.Wang,D.B.Rutledge,\"A60WL-bandClass-E/FOdd2LDMOSPowerAmplifierUsingCompactMultilayeredBaluns,\"IEEEWorkshoponPowerAmplifiersforWirelessCommunications,Sept.13,2004,SanDiego,CA.[14]K.Ji-Yeon,H.Dong-Hoon,K.Jong-Heon,S.P.Stapleton,\"A50WLDMOScurrentmode1800MHzclass-DpowerACKNOWLEDGEMENTThisresearchhasbeencarriedoutinthecompetencecenterCHACH(ChalmersCenterforHigh-SpeedTechnology)inaPage(s):1295-1298,June2005.[15]D.Kuylenstierna,P.Linner,\"Designofbroad-bandlumped-elementbalunswithinherentimpedancetransformation,\"IEEETransactionsonMicrowaveTheoryandTechniques,Volume52,no.12,Page(s):2739-2745,Dec.2004.amplifier,\"InternationalMicrowaveSymposiumDigest,179
