运算放大器经典应用 运算放大器经典应用 运算放大器经典应用R=0J=I=0i R I11+12+l3=l12RAVo= RRI R2 R3RR=R,∥R,MR3∥R特点:调节某一路信号的输入电阻不影响其他路输入与输出的比例关系2.同相求和电路虚短、虚断RRoⅠa=0R113RR+RIRRer roRI—RRs RR=R∥R∥R∥R如果R=RR= RI//R+—+8.2.2单运放和差电路0时:R1n=-B(+V rARI R2RV1=V1=0且2Rp=R3/R4∥RRRRn=R1∥/R21RR=Re*)H=而+h2=B+ViJ。2=RRR3 R4 RR8.2.3双运放和差电路RRRRR,12RAARo1=-RRI R2J2=-R2(x+-)R4 RsV(,v)Vo=RR4、RR2)R例1:设计一加减运算电路设计一加减运算电路,使Vo2Vi1+5Vi2-10Vi;3解:用双运放实现il RVarRAARR如果选R1=Rf2=100K,且R4=100K则:R1=50KR2=20KR=10K平衡电阻R=R//R2//Rn1=12.5KRe=R4//R//R2=8.3K例2:如图电路,求Avf,Ri解:V, Ay3R2R22R2R2I=2VRRJh=l2-11=R2 RIR1-R2R2RRRV RITzRI Ri-R2§8.3积分电路和微分电路8.3.1积分电路电容两端电压与电流的关系:一RA(O)=Cc4(Rve(0)=i(oddi()=-Cdv(t)Ic(t)at +vv(t)12R∫nv()t+vRC Jn积分实验电路100k0.1uF10k100g210kg积分电路的用途将方波变为三角波(Vi:方波,频率50OHz,幅度1V)686m319m47414m78m345346.346,347,348,349349,350,512148mTime(seconds)将三角波变为正弦波(Vi:三角波,频率50OIz,幅度1V)666r321m-24m369m715m694.695.696.697.698.699.699.700.727607mTime(seconds)(Vi:正弦波,频率500Hz,幅度1V)745m379r14r352m7181.01.081.0∈1.081.081.01.0E1.085964Time(seconds)思考:输入信号与输出信号间的相位关系?(Vi:正弦波,频率200Hz,幅度1V)1663m321m21m-363m705012,22,3,22,22,2.22,23,232603Time(seconds)思考:输入信号频率对输岀信号幅度的影响?积分电路的其它用途:去除髙频干扰将方泼变为三角波移相在模数转换中将电压量变为时闫量§8.3积分电路和微分电路8.3.2微分电路i(0)=cavo)Rv()=2∫4()dAdvi(t) vo(t)ic(=CRRVo((=-RO微分实验电路回囚回10k0.1uF200g1 5把三角波变为方波(Vi:三角波,频率1kHz,幅度0.2V)205m1136m68268m340m-599u3nn 09-69m346m-138m-688m26r258258259259259260260260,590832mTime(seconds)输入正弦波(Vi:正弦波,频率1KHz,幅度0.2V)265m176r88440r561u89445m-17ar888r0-26549549550550550550551551.497167Time(seconds)思考:输入信号与输出信号间的相位关系?(Vi:正弦波,频率500Hz,幅度1V)