差分運放誤差分析

差分運放誤差分析RR運放輸入電壓u,u，失調電壓V，開環(huán)差模電壓放大倍數(shù) Ad>105，輸入偏置電流+ - IO vdi+'15,失調電流+RRR-42u-uVu-u= H+RRR-42u-uVu-u= H+ in +R R31u-uVu-ui= + ref =R R42uVuu=(o+in—I)R+R R+ +31uuu=(—o^+ 呼—i)RR R-42u=A(u—u—V)ovd+ —IO(你+Vk—i)R—(^og+R R+ +R14對多輸入和、差電路：運放輸入阻抗設計值為R,實際值R,R相對誤差6對多輸入和、差電路：+-(1+6)R(1+6)R—+u

=―o+3u-^g4即R相對R的相對誤差為6-+VuinR1+V么RR2Vuu+ in— HRR

1+Vuuref— RR2—u乙一^—i)RR-211V1+RRR+3111V1TOC\o"1-5"\h\z1 V1 u—u( + )=o+RR R3131 V1 u—u( + )= +-RR R424u=V+fIOAvd上=(1+6)R+即上竹=1+6R 34RRR 344 3 + 3u+oR-i-)Ru+oR-i-)RR3=(Vio+—i)R—(1+6)u—+ 3 34og12+vd+uR Vu Vu RAu=(V+o)3+6u—(加一i)R+(rf—i)R 3oIOAR34og R+ 3 R— —R12+VuR一f——)RRR32+Au=(Vo IO+6u+(I -i6)R-34ogIO-- 3對差分電路，輸入差分電壓Au=u-u，輸出差分電壓Au=u-uininref oooguRuuRAu = (V +——)亠+8u+(I一i8 )R 一 (—i^n - ref 一)RoIOAR34ogIO-- 3RRR3vd+12+K=R13R1?R=(1+8)K即鼻R=1+8RR2113RR 21+2)R3+2Au=u(V+r+8u+(I—i8)R—K(Au—8u)oIOAR34og IO -- 3 13 in 21refvd+Au=-KAu+￡o13 inuR￡=(V+—o-)3+8u+(I—i8)R+K8uIOAR 34ogIO-- 3 1321refvd+uR￡|<(V+—)—+8u+(I+18)R+K8uIOAR 34og IOIB— 3 1321refvd+對普通共地運放，U=Uf=0,ogref￡|<(V+JR+(I+I8)RIOAR IOIB- 3vd+當電阻精度為8，則8<28,8<48,8<48- 34 21uR￡|<(V+o)3+48u+(I+218)R+4K8uIOAR og IO IB3 13refvd+選擇R3=R4,R1=R2為相同溫度系數(shù)的電阻，相同偏大或偏小方向的阻值，且保持溫度一致則8<8,8<8,8<8- 34 21￡|<(V +作)R+8u+(I +18)R+K8uIOAR ogIOIB3 13refvd+i8<I8《I--IB-IOuoAvdVuoAvdVIO￡<VR+8

IORu34og+IR+K8uIO3 1321ref例：LM224運放，V"=7mV,T=0.1uA,I=0.3uA,R1=R2=2040K,R3=R4=10K,IOIOIBu=310V,u=0V,u=0V,R=R=9.95K,K13=0.49%ref og o + -￡|<7mV*1.005+0.1uA*10K+0.49%*0.01*310V=23.3mVAuouR=(V+f) 3osKR++8u—Ku+(i—i-)R+(1+8)K34og31in +u34 31refAuo=-KAu +(i31 inu―o-3uuu+ in- + rf)(1+8)RRR1 4 2+yu*n_y^rf=(V+

RR12———°g-RR34Au—8uogos o 34_og+RR

31R=R(1+8),R=R(1+5),K2 1 2 4 3 4u34og-IR)R3兀34+-R3+++os+1+(—+y——i)8osR4u+1++R4os+yuin_yh=(VR2y紅rf—R2i)8+1os=(Vosy紅ref_R2u+(―ogR4Au—8uyuyu o 34og+ in— ref_R RR3 1 2Au—8uuu o 34_og+in f=(VR RR3 1 2(R+才)(1+入)—++器)(1+824)=匕+如R+13 1 4 2ogi)8os+uo)—+1 +i8 —i8KRos+13 -24os+i8 -+138一241-(1R-(~R~111RR+311+R3+RR4)*(1+8J=(T+A+824)13(1I8)R13工丄R=(1+8 )R3 34in(—inR(—inRref(―inR°gos(1I8)R24(1+8)R■oginref■ogR*(1I8)13R*(1I8)24i)*R*(1+8)13—i)*R*(1I8)—24u)*R*(1+8)—(—^13R13■og—