运算放大器的内部结构(741)

12-11.OP2.7413.7414.7415.CMOSOP12-2OPBufferCC-K12-3741AB12-4741npn:IS=10-14A,b=200,VA=125Vpnp:IS=10-14A,b=50,VA=50VISA=0.25×10-14A;ISB=0.75×10-14AmA73.0k39V)27.030(=Ω×-=REFIWidlarcurrentsource0.75IREF0.25IREFOFFCurrentfeedbackloop41010REF4101011lnRIIIVRIVVCCTCBEBE==-IC10=19μA12-5CurrentfeedbackloopofthefirststagePCIIb/2129+=A5.94321m==≈=CCCCIIIIIC10=19μAIC1,2→IC8→IC9IC9+IBB=IC10→IBB→IC1,2IBB47.5nAA/2005.921===mBBIIInputbiascurrent12-6Loadofthefirststageamplifier9.5μA9.5μA1kΩ×9.5μA=9.5mVmV517ln6==STBEIIVV526.5mV526.5mV/50kΩ=10.5μAR1,2R3Q7VBE12-70.75IREF=550μAmV618ln1717==SCTBEIIVV100Ω×550μA+618mV=673mVIC16=673mV/50kΩ+550μA/200=16.2μABiascurrentofthesecondstage12-8Output-statebias0.25IREF=180μA180μAIE18VBE18=0.6V~0.6V~15μAVBE18=588mV165μA0.8μA15.8μAVBE19=530mVVBB=1.118V20201414lnlnSCTSCTBBIIVIIVV+=IS14=IS20=3×10-14AIC14=IC20=154μA12-912-10741Inputstage:active-loaddifferentialamplifier0V0V0V221meiomgriG≈=≡aueNidrR)1(4+=bRo4Ro6oemoorrrgrR2)]//(1[4≈+=p)]//(1[26RrgrRmoop+=12-11Smallsignalmodelfortheinputstageof741uiRidGm1uiRo1C6Ω=××=+=M1.2A5.9mV252014)1(4mbeNidrRΩ×=≈=k63.221221memgrGaΩ=ΩΩ×=+==M7.6)M2.18//()M26.52()]//(1[//2//2641RrgrrRRRmooooop12-12Smallsignalanalysisforthe2ndstage---gainstageΩ≈++++=M4)])(1//()[1(81717916162RrRrReeibbmA/V5.6))(1()//(//1217281717171617917928178171717≈≡++=++=+≈icmeieiiieebciGRrRrRRRRRrRriubuuRi17Ω=ΩΩ=⎭⎬⎫⎩⎨⎧+++++ΩΩ=⎭⎬⎫⎩⎨⎧+++++==k4.73)k1.380//()k9.90(1.01.9)]1200/(670054.1//[501.02001)k3.227//()k9.90()]1/(//[1////817161169817171317132RrRrRRrrRRRoeoBooBoopbboeBeoCrRrRRR⎥⎦⎤⎢⎣⎡+++≈pb1ui2Ri2Gm2ui2Ro2C17B16ui2Ri2-Gm2ui2Ro2Ro2C17B1612-13Outputstageof741Q14Q20ONQ20ON5mARi3Ω≈Ω×Ω=++≈M7.3)k250//k280(50)](//[20201323233LeAoeiRrrrRbbΩ=Ω⎟⎠⎞⎜⎝⎛++=⎟⎟⎠⎞⎜⎜⎝⎛++≈+≈37507340013950151232232020202320bbboeeoeoRrrRrRfolloweropen-circuitgain112-14Gainandfrequencyresponseofthe741dB8.106V/V720,21898.0)8.467(2.476037.0224.7337003700)4.735.6)(4000//6700(26.51))(//(23322211==×-×-=++×--≈++--=oLLoiiomiomioRRRRRRRGRRGmuuCC12-15pF14070469pF30|)|1(2=×=+=ACCCeq1MHz984kHzHz5.4rad/s4.28)M4//M7.6(pF140701)//(1021≈====ΩΩ==HTHioeqHfAffRRCw|A|(dB)A0=107dB0f3dB~4.5Hzft~1MHz-20dB/decade12-16Slewrate(SR)(V/s)full-powerbandwidthOFF2I2IsV/63.0pF30µA5.922SR2)(mu=×===CCOCItCIt12-17CMOSOPRzero12-18Folded-cascodeCMOSOPamp