How to calculate gain of diff amp

[karnel]

Can someboby give a quick tip how to calculate gain of such type diff amp?

 

[karnel]

To me it looks G = (R3+R4+R5)/R3
Right?

 

[CMOS]

You schematic is incomplete. You have 2 inputs and 2 outputs ! There should be one more stage on the output side.

 

[flyingsky]

hi
i think the circuit you used is int the file, a ic finished included your circuit.

 

[LvW]

The calculation is rather simple:

*For ideal opamps the difference between both input signals (Vin1 and Vin2) is identical to the voltage across R3 (because the voltage between the opamp (+) and (-) terminals is practically zero).
* When the difference between both output voltages is called (Vout1-Vout2) there is a simple voltage division between both differences:

Vin=(Vin1-Vin2)=R3/(R3+R4+R5)*(Vout1-Vout2).

* Thus the gain (Vout1-Vout2)/(Vin1-Vin2)=Vout/Vin=1+(R4+R5)/R3
(as given already by KARNEL in his answer).