AN427 EZRADIOPRO Si433X & Si443X RX LNA MATCHING英文文献资料

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1、AN427EZRADIOPRO™Si433X&Si443XRXLNAMATCHING1.IntroductionThepurposeofthisapplicationnoteistoprovideadescriptionoftheimpedancematchingoftheRXdifferentiallownoiseamplifier(LNA)ontheSi433xandSi443xfamilyofRFICs.Wedesiretosimultaneouslyachievetwogoalswiththematchingnetwor

2、k:MatchtheLNAinputtoa50sourceimpedance(i.e.,theantenna)Provideasingle-endedtodifferentialconversionfunction(i.e.,abalun)Thematchingprocedureoutlinedinthisdocumentwillallowforachievingthegoalslistedabove.Forthoseuserswhoarenotinterestedinthetheoreticalderivationoft

3、hematchnetwork,butarejustconcernedwithquicklyobtainingmatchingcomponentvalues,refertotheSummaryTablesshownin"4.1.8.SummaryTableof3-ElementMatchNetworkComponentValuesvs.Frequency"onpage15and"4.3.7.SummaryTableof4-ElementMatchNetworkComponentValuesvs.Frequency"onpage21

4、.MeasurementswereperformedontheSi4432-V2butareapplicabletootherrevisionsofthedevice.2.MatchNetworkTopologyTheLNAontheSi443xfamilyofchipsisdesignedasadifferentialamplifierandthushastwoinputpins(RXpandRXn)ontheRFIC.Itisnecessarytodesignanetworkthatnotonlyprovidesaconju

5、gatematchtotheinputimpedanceoftheLNAbutalsoprovidesabalanced-to-unbalancedconversionfunction(i.e.,abalun).Wewillconsideruseoftwobasictopologiesofmatchingnetworks,withtwovariationsononeofthetopologies.2.1.Three-ElementMatchNetworkThesimplestmatchnetworkthatmaybefabric

6、atedfromdiscretecomponentsiscomprisedofthreediscreteelements.Wewillconsidertwodifferentformsofthis3-elementmatchnetwork:onewithahighpassfilter(HPF)response,andonewithalowpassfilter(LPF)response.TheRXpandRXninputsoftheSi443xRXLNAareinternallycapacitively-coupled;there

7、isnoneedtoprovideexternalcouplingcapacitorstoactasdcblocks.2.1.1.Three-ElementHPFMatchNetworkA3-element(C1-L-C2)HPFmatchingnetworkisshowninFigure1.Thismatchingnetworkhasthevirtueofrequiringaminimumnumberofcomponentsbutresultsinslightlysub-optimalperformance.Itisnotth

8、eoreticallypossibletoachieveaperfectlybalancedsingle-ended-to-differentialconversionfunctionwiththisnetwork.Aswillbedemonstrated,th