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ID:17577615
大小:2.02 MB
页数:124页
时间:2018-09-03
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1、SomeDesignAspectsonRFCMOSLNAsandMixersAnna-KarinStenmanDepartmentofElectroscienceLundUniversityP.O.Box118,S-22100LUNDSWEDEN©2001Anna-KarinStenmanNo.26ISSN1402-8662PrintedinSwedenKFSABLund,December2001ToMarkusAbstractThisthesisdealwithtwopartsofaradioreceiver.Thelownoiseamplifier(LNA)andthemi
2、xer.AtunedRFfront-endamplifierinCMOSwithanoperatingfrequencyaround1.8to2GHzhasbeeninvestigated.Asymmetricdesignhasbeenusedtoimprovelinearitywithpre-servedpowerconsumption.Inthiscaseithasbeenaparallelconnectionofcomplementarydevices.Thesymmetricsolutionallowstheuseofinductorpairsintransformerc
3、onfigura-tiontoimprovethegainofthecircuit.Theinputimpedancehasbeencontrolledbyaninductiveseriesfeedbackofatransconduct-ance.Anextendedinvestigationhasbeenmadetodeterminetheeffectofthecapacitiveshuntfeedback,traditionallyignored,aswellastheeffectsofotherinternalparasitics.Sim-ulationresultssh
4、owsthatforarequiredinputresistanceandoperatingfrequencyamaxi-mumtransconductanceofthetransistorcanbefound.Anewapproximationoftheinputresistancewherefound,validforlowfrequenciesandforsmalltransconductances.Themostimportantpartoftheamplifieristhefirststage(theinverter)asitwillaffectbothinputimpe
5、danceandnoise.Analysisoftheoptimumnoisefigurebothwiththecapacitiveshuntfeedbackexcludedandincludedaremadetoshowthatitispossibletorepeatthecal-culationsinthesamemannerbothtimesandtherebybeingabletocomparetheresults.Themajorconclusionofthispaperisthattheshuntfeedbackcannotbeignoredandthatgoodd
6、esignmethodsthereforerequireamoreextendedanalysis.Imbalancesinquadraturedemodulators,basedonapassiveCMOSmixerwithcapacitiveload,hasbeenstudiedwithrespecttoprocessspread.Amathematicalmodelofthemixerhasbeenpresentedwhichexplainsthestatisticalspreadinthemixer.Themixertransferfunctionhasbeendivi
7、dedintoamultiplier,anamplifierandatime-variantfilter,wherethestatisticalspreadwillaffectthefilteringpartofthemix-er.Thefilteristime-invariantifthetimeconstantislargeenoughcomparedwiththelocalos-cillatorfrequency.Afirstapproximationofthemixerfilteristher
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