| 本帖最后由 shizaigaole 于 2011-5-24 14:52 编辑 
 (Ve-V2)/R2 = (V2 - Vi/2)/R4
 
 Ve = R2*(V2-Vi/2)/R4 +V2 = (R2/R4+1)V2 - (Vi*R2)/(2*R4)
 
 V2 = V3
 
 Ve = (R2/R4+1)V3 - (Vi*R2)/(2*R4)
 
 
 Io = (12-Ve)/R1 =(12 - (R2/R4+1)V3 + (Vi*R2)/(2*R4))/R1
 
 Io = (12 - (4*V3)/3 + Vi/6)/100
 
 调整V3使Vi = 0的时候,输出4mA
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