I see that there are multiple ways to bias a simple Common Source NMOS transistor but I want to understand about biasing using current source.
I put up this circuit in SPICE:
The above is simple Common Source Amplifier biased with help of current source without a constant gate voltage. My first question is, "is this really biased with current source? or is it biased with -1.4V below the current source?"
I called this "biasing using current source" because changing the current value changes the operating point and Source potential is not fixed (while operation).
Well, now arises an interesting observation. I see that this circuit amplifies the voltage variations at Gate (which is what i wanted). However, the source potential varies with gate. (acts as source follower). But to amplify, shouldn't the source potential be fixed? Only then Gate-Source potential would vary and produce the output right? So, I wanted to know how current variation happens across the resistor to amplify the signal? (shouldn't the current just stay constant?)