Wnhat are inverting and noninverting inputs to an op-amp connected to?

Question

an inverting amp? open loop amp? noninverting amp? or differential amp?

Answer 1

inverting and noninverting inputs inside the opamp are connected to the first stage differential amplifier.

Externally, it depends on what you are using the opamp for.

Inverting amp, + input to ground, possibly via a resistor. - input to the circuit input via a resistor R1, and to the output of the opamp via a resistor Rf. Gain = Rf/Ri

Non-inverting amp, Rf from output to - input, R1 from there to ground. + input is tied to circuit input. Gain is 1+Rf/Ri.

Diff amp is too complicated to explain in words. Google for a schematic. Basically it's a combination of the first two.

Open-loop: no feedback.

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