1394IEEEJOURNALOFSOLID-STATECIRCUITS,VOL.33,NO.9,SEPTEMBER1998AFrequencyAgileMonolithicQPSKModulatorwithSpectralFilteringand75DifferentialLineDriverBrentA.Myers,Member,IEEE,ScottBardsley,PatrickLandy,TimothyBell,Member,IEEE,andRobertRossAbstract—ThismonolithicmodulatorcombinesbothdigitalToassurespuriousfrequencycomponentsinadjacentchannelssignalprocessingandanalogtechniquestorealizeahighbit-areattenuatedbygreaterthan40dB,thechargeredistributionratequadraturephase-shiftkeyed(QPSK)modulator.ItincludestypeD/Aconvertershave1:5analoginterpolatingfiltersadigitalbasebandpulseshapingnetwork,analogquadraturemodulator,agilecarriergenerator,spectralshaping,andtrans-whichalongwithD/Arolloffprovide37dBofD/Aimagemitpowercontrolforinterfacingtowirelinetransmissionme-rejection.Thispermitstheuseofasingle-orderreconstructiondia.Nominaldataratesare256kbit/swithacarrierrangeoffiltertoeliminatedigital-to-analogconverter(DAC)replicas.8.096–20.128MHzin32kHzsteps.Maximumoutputlevelis62Thebasebanddataisinputtothequadraturemodulatorthrough"dBmVintoa75load.Thefeaturesof1.2mmixedsignalanexternalcapacitortoeliminateanydcoffset.ThemodulatorBiCMOStechnologypermitbothsignalprocessingandpowerlinedriverstobecollocatedwhileachievingbetterthan85dBconsistsoftwobalancedmultiplierswithacommonresistivecross-talkisolation.loadtosumtheIandQchannels.Thequadraturecarriersaregeneratedbythesynthesizer,IndexTerms—Filters,linedrivers,modulators,quadraturephase-shiftkeying.whichcombineshighspeeddifferentialemittercoupledlogic(ECL)andstandardCMOSlogictoachievethenecessaryrangeandresolution.ThesynthesizeralsogeneratesacurrentI.INTRODUCTIONproportionaltooperatingfrequency,whichisusedtotunetheECENTactivityinhighspeedwirelinedatatransmissiontransconductancetrackingfilterthatfollowsthemodulator.Rhascreatedtheneedforlow-costsiliconrealizationsThetrackingfilterassuresthatharmonicsofthemodulatedcar-ofdigitaldatamodulators.Inparticular,datatransmissionrieraresuppressedbyatleast40dBpriortotransmissio