五,
(1)
一级放大- 求和电路
V-设为Vp,V+设为Vn
由虚短和虚断:
Vp = Vn, Ip = In = 0;
那么: Ui1/R1 + Ui2/R2 + Ui3/R3 = -Uo1/R4
得出Uo1 = -(6Ui1 + Ui2 + 2Ui3)
二级放大- 反向放大
V-设为Vp,V+设为Vn
由虚短和虚断:
Vp = Vn, Ip = In = 0;
那么Uo1/R5 = -U0/R6
得出Uo = 36Ui1 + 6Ui2 + 12Ui3
(2)
带入即可:Uo = 36 - 7.2 - 4.8 = 24V.