场效应管基础知识

NPJFET(JunctionFieldEffectTransister)IGFET(InsulatedGateFieldEffectTransister)IGFET--MOSFETMetalOxideSemiconductorFET1.11.1.1MOSMOSEnhancementMOSEMOS(Depletion)MOSDMOSNPD(Drain)G(Gate)S(Source)MOS(EMOS)3-1NMOSFETPSiO2NNDSGPB3-1NEMOS1VGS=0VDSDS0VGSVGS(th)PIDVGSVGSVGS(th)VGS(th)PID1PinversionlayerVGSIDVGS=0VID=0VGSVGS(th)MOSMOSgmgmmA/VgmconstDS==VGSDVIgm∆∆(mS)2VDSVGSVGS(th)VDSIDVDS3-2VDS=VDGVGS=VGDVGSVGD=VGSVDSVDS0VGDVGS(th)VDSVGD=VGS(th)VDSIDVDSVGDVGS(th)SVDSIDabc3-2VDSVGSVGS(th)VDSIDiD=f(vDS)VGS=const3-3VGSIDDVDS3-3VGSIDVDSVGS-VGS(th)23-31NonsaturationRegionVGSVGS(th)VDSVGS-VGS(th)IDVGSVDS]VV)VV(2[l2WCIDS2DS)th(GSGSoxnD−−=µ2(SaturationRegion)VGSVGS(th)VDSVGS-VGS(th)2)th(GSGSoxnD)VV(l2WCI−=µIDVGSID)V1()VV(l2WC)VV1()VV(l2WCIDS2)th(GSGSoxnADS2)th(GSGSoxnDλµµ+−=−−=3VGSVGS(th)ID=0VGS(th)SubthresholdRegionIDVGSIDVGS3-54VDSPNIDPEMOSNP+P+SiO2PEMOS31.1.2MOSDMOSNMOSFET3-5SiO2VGS=0VGS0IDVGS0VGSID=0ID=0VGSVGS(off)VPNMOSFET(a)(b)3-5NMOSFETPMOSFETNMOSFETNPNPNPMOS1.1.3NEMOSDMOSPEMOSDMOSVGSVGS(th)VDSVGS-VGS(th)VGSVGS(th)VDSVGS-VGS(th)]VV)VV(2[l2WCIDS2DS)th(GSGSoxnD−−=µVGSVGS(th)VDS≤VGS-VGS(th)VGSVGS(th)VDS≥VGS-VGS(th))V1(]VV[l2WCIDS2)th(GSGSoxnDλµ+−=4MOS1.1.4vGS=vGSQ+vgs,vDS=vDSQ+vds,iD=IDQ+iddsQDSDgsQGSDDQDSGSDvvivviI)v,v(fi∂∂+∂∂+==igsgmvgs--D+vdsrdsS+vgsGgm:Transconductance1/gds:outputresistancerds:1/gdsdsdsgsmDQDdvgvgIii+≈−=)V1(Il2WC2)V1)(VV(lWCvigDSQDQoxDSQ)th(GSGSQoxQGSDmλµλµ+=+−=∂∂=WC2lIVVoxDGS(th)GSµ=−DQdsDQoxmIg,,,Il2WCgλµ=≈5GD++--µvgsrdsvdsvgsigsµ=gmrdSmQusDgvigmuη=∂∂=gmvgsrdsvds-+vgs+gmuvus-CgdCsuCgdCdsgCgudsCgsCgdCgsgdCdss1.1.561.21.2.1NPNPNNPN3-2-1NJFET3-2-2NPJEFETDSGNP+P+7DSGPN+N+DSGP+P+DSGP+P+--++3-2-3NJFETVDS=0VGSPNNVDS=0VGSVGS=VGS(off)DSGP+P+GDSGP+P+GIDPNPNPNVGS=VGSoff1.2.2N8PPNN(a)(b)1VGSVGS(off)VDSVGS-VGS(off)])VV(VV)VV1(2[II2)off(GSDS)off(GSDS)off(GSGSDSSD−−−=2VGSVGS(off)VDSVGS-VGS(off)2)off(GSGSDSSD)VV1(II−=3VGSVGS(off)ID=04VDSV(BR)DSPNID9