Question

In the saturation region of a MOSFET, the drain current is primarily controlled by

• A. \(V_{DS}\)
• B. \(V_{GS}\)
• C. Drain resistance
• D. Temperature only

Hint:

In the saturation region, \[ \boxed{ I_D\propto(V_{GS}-V_T)^2 } \] and is almost independent of \(V_{DS}\).

Answer 1

The Correct Option is B

Step 1: Recall the MOSFET saturation condition. For an enhancement MOSFET operating in saturation, \[ V_{DS}\ge V_{GS}-V_T. \]

Step 2: Identify the controlling quantity. The drain current is approximately \[ I_D = \frac{k}{2}(V_{GS}-V_T)^2, \] showing that it mainly depends on the gate-to-source voltage. Hence, \[ \boxed{V_{GS}} \] controls the drain current. Therefore, \[ \boxed{(B)} \] is the correct answer.