清华大学电路原理课件4

1PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004IOpAmp4IIidealOpAmpIIIPrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004IOperationalAmplifier••4050.•60..PrescottP4108125mm2LM324OpAmp102,120mm22PrinciplesofElectricCircuitsLecture4TsinghuaUniversity20041.a:invertinginputu-b:noninvertinginputu+O:output,uoOpAmpAopen-loopvoltagegain105~108+_ududu+u-uo_+A+abo:groundº+__+u+u-º+_uoao+_udud_+A+bVCCVCC:workingvoltagePrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004WkM3PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004ud=u+uuoud0|ud|Uds,uo=AududUds,uo=UsatudUds,uo=Usat2.UsatUsatUdsUds+_udud+_u+_+u_+uo_+A+UdsUsat=13V,A=105OpAmpUds=0.13mVPrinciplesofElectricCircuitsLecture4TsinghuaUniversity20043.RiRo+_A(u+u)RoRiu+u+_udud+_u+_+u_+uo_+A+4PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004+_A(u+u)RoRiu+uOpAmpÆÆ0+_A(u+u)u+uPrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004+_uo_+A++_u1+_u2()12uuAuo−=1u1u2ÅÆuoui2OpAmpAÅÆOpAmp3OpAmpAÅÆuoud05PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004feedback+_uo_+A++_uiR1Rf12R1Rf-Au1+_+_u1+_uo+_uiiifoiRuuRuu−=−111ouAu=−1()11ARRRARuuffio++−=PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004+_uo_+A++_uiR1Rf12()11ARRRARuuffio++−=1u1u2ÅÆuoui2OpAmpAÅÆOpAmp3OpAmpAÅÆ1RRuufio−=AVVV6PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004+_A(u+u)RoRiu+u+_A(u+u)u+uOpAmpÆÆ0+_udud+_u+_+u_+uo_+A+AÆu+u-uo_+∞+i+i+++___PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004A→∞uoud≈0,u≈u()Ri→∞R0→0,i+≈0,i≈0()uoud0()u+u-uo_+∞+i+i+++___IIIdealOpAmpUsatUsatUdsUds7PrinciplesofElectricCircuitsLecture4TsinghuaUniversity20041.;iouu=+∞++_uo+_uiIIIPrinciplesofElectricCircuitsLecture4TsinghuaUniversity200412122uRRRu+≠R2RLR1+_u2+_u1_+∞++_uiR1R2RL+_u212122uRRRu+=8PrinciplesofElectricCircuitsLecture4TsinghuaUniversity20042u+=u=0i=0i+=0i2=i1i1fouRRuRuRu−=−=fo1i(1)R1Rfuo()ui2Rf,+_uo_+∞++_uiR1Rfi1i2iuu+ii1=ui/R1,i2=-uo/RfPrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004VCVSºººº+_u1i1+_uoi2+_11fuRR−+_uo_+∞++_uiR1Rfi1i2iuu+ii1fouRRu−=9PrinciplesofElectricCircuitsLecture4TsinghuaUniversity20043.u+=u=uii+=i=0o212iuRRRu+=i21i221o)1(uRRuRRRu+=+=+∞+RiuiR1R2uui+_uo+_iPrinciplesofElectricCircuitsLecture4TsinghuaUniversity200400====+−+−iiuufiiii=++321foRuRuRuRu−=++332211)(332211ouRRuRRuRRufff++−=4.+_uo_+∞+R2Rfiu+uR1R3u1u2u3i1ifi+i3i2+++___1OpAmpKCL2OpAmpKCL1OpAmpKCL2OpAmpKVL10PrinciplesofElectricCircuitsLecture4TsinghuaUniversity20045.+_uo_+∞++_uiR1Rfi1i2iuu+i+∞+RiuiR1R2uui+_uo+_ii1fouRRu−=i21o)1(uRRu+=PrinciplesofElectricCircuitsLecture4TsinghuaUniversity20045.+∞+R1RfR1uui+_uoi+_u1+_u2foRuuRuu2112−=−21111uRRuRRuffo⎟⎟⎠⎞⎜⎜⎝⎛++−=11PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004+_uo_+∞+R1RfuR1Rf+_u1+_u221uRRRuff+=foRuuRuu−=−11()211uuRRufo−−=6.PrinciplesofElectricCircuitsLecture4TsinghuaUniversity20047+∞+RiR1RL+_uii1Ruii=12PrinciplesofElectricCircuitsLecture4TsinghuaUniversity2004822Riu−=RiuR2111iRR−==21uu=2211iRiR=R++∞R2R1i1i2u1u2++KVL