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1、April2011CompactPowerAmplifierforLTEMobileTerminalsUsingCouplingVariationReductionTechniqueByYangLi,DmitriPrikhodko,YevgeniyTkachenkoandRickZhu,SkyworksSolutions,Inc.Tomeettheoverwhelmingdemandforhighdataratemobileapplications,3GPPlong-termevolution(LTE)isquicklydevelopingaroundtheworldasamajor
2、stepforwardincellulartechnology.InDecember2009,theworld’sfirstcommercialLTEserviceopenedbyTeliaSonerainStockholmandOslo.InSeptember2010,thefirstUScommercialLTEservicelaunchedbyMetroPCSinLasVegasandDallas.OnDecember5,2010,VerizonWirelesslaunchedits4GBand13LTEnetworkin38marketscovering110millionp
3、eopleintheUnitedStatesandtargetingfullnationwidecoveragein2013.Table1summarizesworldwideLTEfrequencybandsandtheregionsinwhichthereisdeployment.LTE'sradioaccessiscalledevolvedUMTSterrestrialradioaccessnetwork(E-UTRAN).TheairinterfaceofE-UTRANisbasedonorthogonalfrequencydivisionmultipleaccess(OFD
4、MA)inthedownlink(DL),andsinglecarrierfrequencydivisionmultipleaccess(SC-FDMA)intheuplink(UL)direction.ItsupportsQPSKand16QAM.Itsbandwidthcanbesetupas1.4,3,5,10,15and20MHz.Withsuchcomplicatedradioaccessandmodulationscheme,LTEimposestoughrequirementsonthePAMdesigns,especiallyonitslinearpower,effi
5、ciencyandsize.LTEapplicationscenarionaturallyrequireshighefficiencytoextendbatterylifeinuserequipment(UE).However,itsSC-FDMAisnotreally“SingleCarrier”;itisessentiallyamulti-carrierschemewithhighpeak-to-averagepowerratio(PAPR).Table2showstheprobabilitybasedoncomplementarycumulativedistributionfu
6、nction(CCDF)curvesforWCDMA,HSDPA,LTEandWiMAX.ItcanbeseenthatalthoughPAPRofLTEislowerthanOFDM,itisstillsignificantlyhigherthanWCDMA.Withatypicaltestsignal10MHz12ResourceBlocksQPSK,wheremaximumpowerreduction(MPR)isequalto0dB,itsPAPRisapproximately2.8dBhigherthantheWCDMAsignalwhenCCDFisequalto0.01
7、%.Higherlinearityrequirementincreasesthebackoffofoutputpowerandresultsinefficiencydrop.ReuseofWiMAXPAinLTEcanmeetlinearityrequirements,butitsPAEisfacedwithseverechallengesfromthetalktimepointofview[3].LTEUEadoptsmulti-bandandmulti
