Hi,
The above image is of two common drain amplifiers. From what I know, the PMOS common drain amplifier shifts the input voltage up by ~Vth(threshold voltage) and the NMOS common drain amplifier shifts the input voltage down by ~Vth. Since the PMOS common drain is not subjected to bulk effect it has a gain close to 1 (~0.99, ~1.01). The NMOS common drain on the other hand will have bulk effect causing its gain to drop lower than 1 (~0.9 maybe).
Q1: Is there a way to increase the gain of the NMOS common drain amplifier efficiently to ~1?
Q2: I'm not 100% sure how to vary the threshold voltage, could changing the biasing of the transistor vary the threshold voltage?
Thanks.