What is the key difference between a MOSFET operating in the saturation region versus the triode (linear) region?
In the triode (or linear) region (Vds < Vgs - Vt), the MOSFET acts like a voltage-controlled resistor, and the drain current (Id) is highly dependent on both Vgs and Vds. In the saturation region (Vds >= Vgs - Vt), the channel is 'pinched off' near the drain, and the drain current becomes relatively independent of Vds, primarily controlled by Vgs. This makes the saturation region ideal for use as an amplifier.
