Operation of MOSFETs as Gate Voltage Changes

https://electronics.stackexchange.com/questions/678861/overdrive-voltage-of-nmos-vs-pmos

$$V_{OV}=V_{GS}-V_T$$

• Is valid for both PMOS and NMOS.

• All three voltages must have the same sign.

• $V_T$ is the gate voltage ($V_{GS}$) required to activate the gate.

  • For NMOS that’s positive (to chase away holes in p-substrate and attract electrons from n-wells).
  • For PMOS this is negative (to chase away electrons in n-substrate and attract holes from p-wells.)

• As we increase/decrease the gate voltage to increase current flow, $V_{OV}$ is the extra voltage after it crosses $V_T$.