an active inductor-based vco with wide tuning range and high dc-to-rf power efficiency

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1、462IEEETRANSACTIONSONCIRCUITSANDSYSTEMSII:EXPRESSBRIEFS,VOL.58,NO.8,AUGUST2011AnActiveInductor-BasedVCOWithWideTuningRangeandHighDC-to-RFPowerEfficiencyJiangtaoXu,StudentMember,IEEE,CarlosE.Saavedra,SeniorMember,IEEE,andGuicanChenAbstractAnactiveinductor-basedvoltage-controlledoscilla-tor(VCO)w

2、ithawidefrequencytuningrangewasdesignedandfabricatedusingastandard0.13-µmCMOSprocess.Theoscilla-torhasanLC-tanktopologywithcross-coupledtransistors,andtheactiveinductorwasrealizedusingapairoffullydifferentialveryhigh-speedoperationaltransconductanceamplifiers.Duetothedifferentialnatureoftheindu

3、ctor,theevenharmonicsoftheoutputsignalweremuchreduced.MeasuredresultsshowthattheVCOistunablefrom833MHzto3.72GHz,representingatuningrangeof127%.TheVCOcanproduce−0.9dBmofradio-frequencypower.Thecorecircuit,excludingoutputbuffers,consumes13mWfroma1.2-Vsupply.IndexTermsActiveinductor,feedbackresis

4、tance,high-linearityhigh-speedoperationaltransconductanceamplifier(OTA),highoutputpower,voltage-controlledoscillator(VCO),widetuningrange.I.INTRODUCTIONFig.1.Simplesingle-endedgyrator-Cactiveinductor.HERECOGNITIONthatactiveinductor-basedvoltage-toourknowledgeisthehighestreportedtodateforanactiv

5、eTcontrolledoscillators(VCOs)canhaveexceptionallywideinductor-basedVCOandiscomparablewiththepowereffi-frequencytuningranges,exceeding100%,andthattheycanbeciencyofaVCOusingaphysicalLCtank.optimizedtoconsumesmallamountsofpowerhassparkedagoodamountofinterestinthesecircuitsoverthelastseveralyears[1

6、][4].AnotherincentivetoexploretheuseofactiveII.ACTIVEINDUCTORDESIGNinductorsinVCOsarethesavingsinchipspacerelativetoA.BasicConceptsusingphysicalinductors,particularlywhenalargeinductanceisrequiredatrelativelylowfrequencies.AcommonlyusedactiveinductortopologyisdepictedinInthisbrief,wepresentaVC

7、OcircuitthatusesadifferentialFig.1,whichconsistsoftwotransistorsthatarearrangedtoactiveinductor.Theactiveinductorisbasedonagyrator-Cfunctionasanimpedance-invertingnetwork.Thegyratorin-topologywithveryhigh-speedoperationaltransconductanc