amwygah
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Thanks for all your discussions at first.
1).Just as what godfrey has said，I did mean that Vid = differential input voltage and Vic = common mode input voltage.
2).my question comes from the pdf at the end of this message.
3).I did know this circuits can be used to test CMRR after the op amp was manufactured.
But i am confused about the result of the gain, because the result in the pdf is 2 times bigger than mine.
4).Thanks godfreyl and FvM very much, i did make a mistake on the sign of Vid.
it should be Vid = -Vout*R1/(R1+R2), and then the result should be given by FvM
5). And at last, thanks anybody takes part in my thread very much, include FvM,LvW,dselec,godfreyl,varunkant2k,and so on...
6).Similar to godfreyl
And my result is Vout/Vin = 1000 * Acm / (1001 - Acm * 0.5 + Adm)
and then it can be approximately Vout/Vin = 1000 * Acm / Adm.
1).Just as what godfrey has said，I did mean that Vid = differential input voltage and Vic = common mode input voltage.
2).my question comes from the pdf at the end of this message.
3).I did know this circuits can be used to test CMRR after the op amp was manufactured.
But i am confused about the result of the gain, because the result in the pdf is 2 times bigger than mine.
4).Thanks godfreyl and FvM very much, i did make a mistake on the sign of Vid.
it should be Vid = -Vout*R1/(R1+R2), and then the result should be given by FvM
5). And at last, thanks anybody takes part in my thread very much, include FvM,LvW,dselec,godfreyl,varunkant2k,and so on...
6).Similar to godfreyl
And my result is Vout/Vin = 1000 * Acm / (1001 - Acm * 0.5 + Adm)
and then it can be approximately Vout/Vin = 1000 * Acm / Adm.
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