Here I try to recreate the innards of an OPAMP with a 2-stage configuration.
I then mimic the OPAMP circuit topology to the right, which has a gain A=3.
Ultimately, I used 3 switches to represent the input and output pins (2 input, 1 output).
It can be observed that it behaves almost like it.
THE TWO STAGES:
1st stage: Differential Stage, for high gain. Where the differential inputs are connected. Here it should be clear why the inputs of an OPAMP are considered very high impedance (gate-body of MOSFET is like a capacitor, they are open)
2nd stage: Amplifier Stage, for high output swing. This is where the output is generated.
IMPROVEMENTS:
I am not an expert in Analog design, and I am aware that this is a badly made OPAMP I've only arbitrarily adjusted the values of the OPAMP internal circuitry so as to make it work almost like an OPAMP.
Any suggestions on how I might select the values and parameters (voltage, current ref, FET dimensions)?
Some intuition to how I might select these values would really help.
