SSA_stability

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1、SSA_stabilityEXAMPLE1-STABILITYANALYSISOFSMALLSIGNALAMPLIFIERInthisexamplewewillexaminethestabilityofabipolarjunctiontransistor(BJT)amplifier.TheBJTdeviceusedisBFR92A,anNPNsurfacemounttransistorfromPhillipsSemiconductor.Weareinterestedinusingthetransistortodesig

2、nanamplifieroperatingat418MHz.Step1–DesigntheDCbiasingcircuitAcollectorcurrentofbetween3.0mAto5.0mAisdesirable.Thefollowingcircuitisconstructedintheschematiceditor.ThemodelforBFR92AisprovidedbyPhillipsSemiconductorandisdefinedaccordingtoSPICE3format.V_DCSRC1DCVd

3、c=3.3VLDC1L=1.0uHR=RR=6.8kOhmBJT_ModelBJT_NPNBFR92ABJT1NPN=yesBr=18.11Cjc=5.466E-013Re=1.165Model=BFR92APNP=noIkr=1.28155Vjc=0.3808Rc=2.320Area=Bf=102.639Isc=2.799E-016Mjc=0.2029Kf=Region=Ikf=3.201Nc=1.0754Xcjc=Af=Temp=Ise=4.011E-015Var=3.369Fc=Kb=Mode=nonlinear

4、Ne=1.577Nr=0.9962Cje=8.905E-013Ab=Vaf=62.672Tr=Vje=0.60Fb=RNf=0.997275Eg=1.110Mje=0.2586Ffe=Tf=1.5497E-011Is=4.119E-016Cjs=Lateral=noR=4.7kOhmRXtf=39.140Imax=Vjs=AllParams=Vtf=2.153Xti=3.000Mjs=R=100OhmItf=0.2138Tnom=Rb=10.0Ptf=Nk=Irb=1.0E-06Xtb=Iss=Rbm=10.0Appr

5、oxqb=yesNs=RbModel=MDSFigure1–ThecircuitforDCanalysis.ThecollectorcurrentfromDCsimulationisIc=4.21mA.Hints:Selectthe“Devices-BJT”palettefromthecomponentpalettelist.From“Device-BJT”palette,selectthistoinsertaNPNtransistor.SelectthistoinsertamodeldefinitionforNPNt

6、ransistor.F.Kung1March2001RL121eSSA_stabilityStep2–ACAnalysisTheACcircuitisconstructedasshowninFigure2.Thetransistormodelincludesthedieandpackageparasitics.SmallsignalS-parametersimulationisperformed.Themacro“Stab_Fact”isinvokedtodeterminetheRoulettestabilityfac

7、torkatvariousfrequencies.DeactivatethesourcePerformingSmallSignalS-ParameterSimulationandloadstabilitycirclesS_ParamSP1S_StabCircleStart=50.0MHzs_stabcir1Stop=3.0GHzsource_stabcir=s_stab_circle(S,51)Step=10.0MHzL_StabCircleLl_stabcir1load_stabcir=l_stab_circle(S

8、,51)V_DCL=1.0uHStabFactSRC1R=k1Vdc=3.3Vk_amp=stab_fact(S)TransistorModel-IncludingthepackageanddieparasiticRLCCR=6.8kOhmL=0.1nHC=1.0nFR=C=100fFCTermBJT_NPNTerm2BJT1C=