houly75
Newbie
Hi all
I'm interesting in instrumentation op amp and I would want to know how I can calculate the differential input impedance and the common mode input impedance of an op amp circuit.
I can't find a serious article or application note that show how I can calculate the input impedance of an op amp with considering real input elements of the op amp (resistance not the capacitance).
The first op amp stage is a simple differential op amp :
**broken link removed**
how I can calculate the common input impedance with considering the impedance of the op amp ? and the same for differential impedance ?
The second stage is an instrumentation stage :
**broken link removed**
same question...
here is the equivalent circuit that I found on the net
**broken link removed**
thanks a lot for your help and sorry for my poor english
I'm interesting in instrumentation op amp and I would want to know how I can calculate the differential input impedance and the common mode input impedance of an op amp circuit.
I can't find a serious article or application note that show how I can calculate the input impedance of an op amp with considering real input elements of the op amp (resistance not the capacitance).
The first op amp stage is a simple differential op amp :
**broken link removed**
how I can calculate the common input impedance with considering the impedance of the op amp ? and the same for differential impedance ?
The second stage is an instrumentation stage :
**broken link removed**
same question...
here is the equivalent circuit that I found on the net
**broken link removed**
thanks a lot for your help and sorry for my poor english