Homework Help: RC Op-Amp Circuit

1. Nov 11, 2009

astonmartin

How would you solve an RC op-amp circuit connected in a non-inverting fashion, such that the second resistor is replaced by a capacitor. This is not the usual differentiator or integrator circuit as far as I can tell?

No specific problem, just generally speaking, how would you approach this

2. Nov 11, 2009

Staff: Mentor

Can you post a sketch of the circuit? I think I can picture what you are asking, but it would be good to be more clear.

In general, you solve all opamp circuits the same way. Assume that there is no voltage between the + and - inputs, by virtue of the high negative feedback gain of the opamp, and assume that there is no input current into the + and - inputs. If there are inductors or capacitors in the circuit, you use the differential or integral relationship between their current and voltage as part of the circuit equations. I usually use KCL equations and solve them.

Then you go back and factor in the non-infinite gain of the opamp, and the non-zero input bias currents, the input offset current and voltage, etc., if applicable to the problem.