Software-definedRadioTransmittersforAdvancedWirelessandSatelliteCommunicationsSystemsbyadminonDecember20,2008Thewirelessandsatellitecommunicationscommunitieshavealwaysbeenlookingforpowerefficientradios.However,thepowerefficiencyisgreatlydominatedbytheefficiencyoftheHYPERLINK"http://rfengineer.net"RFpoweramplifier(PA)inthetransmittingpath.Recently,mostofthecommunicationHYPERLINK"http://www.mwjournal.com/BuyersGuide/buyersguide.asp?CatId=114&ref=AutoArticle"systemsbeingdeployedortobedeployedinthenearfutureusetime-varyingenvelopesignals.Withsuchsignals,PAsarerequiredtooperateintheirback-offregiontomeettherequiredlinearity.Thislinearityisdefinedeitherbytheadjacentchannelpowerratio(ACPR)ortheerrorvectormagnitude(EVM)inthecontextofwirelessapplicationsornoisepowerratio(NPR)insatellitecommunications.Thesettingoftheback-offlevelisgenerallyafunctionoftheinputsignal’speak-to-averagepowerratio(PAPR).Unfortunately,thepowerefficiencyoftheamplifierdecreaseswhentheback-offlevelincreases.Inmostcases,thisleadstothedesignofverylow-efficiencyHYPERLINK"http://www.mwjournal.com/BuyersGuide/buyersguide.asp?CatId=2&ref=AutoArticle"amplifiersthatrequirelargeDCpowermodules,withbulkythermaldissipatorsforfixedterminalsorhaveshortbatterylifeinmobileterminals.Fromthebasestationprospective,theselinearandlow-efficiencyHYPERLINK"http://www.mwjournal.com/BuyersGuide/buyersguide.asp?CatId=2&ref=AutoArticle"amplifiersturnouttobeverycostlytomanufactureandveryexpensiveforthetelecommunicationoperatorswhoruntheinfrastructure.Linearizationtechniquesarebeingusedtoimprovetheachievablepowerefficiency.However,theresultingpowerefficiencyisstillintherangeof15to30percent.1-3RecentadvancesinsemiconductorprocesstechnologiessuchasGaN-andSiC-baseddevices4aremakingthedesignofhighlyefficientswitchingmodeRFHYPERLINK"http://www.mwjournal.com/BuyersGuide/buyersguide.asp?CatId=19&ref=AutoArticle"poweramplifiersafeasiblesolutionforsuchapplications.Tobeabletousesuchpoweramplifiers,theirdesignhastobeconsider