Attached is an amplifier I'm working with. I'm trying to see the effect on common mode noise of the R and C connecting the "+" and "-" of the amp. Can anyone tell me the theoretical gain of this configuration? without doing too much math?
It's not a particularly easy circuit to calculate the gain versus frequency. The easiest way to determine that is just to simulate it in LTspice or other Spice simulator.
The DC gain from the V2 input is just 75k/20k = 3.75.
Attached is an amplifier I'm working with. I'm trying to see the effect on common mode noise of the R and C connecting the "+" and "-" of the amp. Can anyone tell me the theoretical gain of this configuration? without doing too much math?
I don't understand the question. The common mode noise is a parameter of the op amp, not the resistor and capacitor, right? I assume the output is taken from the op amp. If the AC voltage V2 is set to zero, the DC gain of V1 is 3.3321. This will raise the DC level of the output to 3.3321x4.096 = 13.648 volts. This gain was calculated by taking into consideration the values of R1,R2,R3,R4.
I am not going to work out the AC gain unless you really need it. Do you?