Question

The transistor in the circuit shown below has kn = 0.4 mA/V^2, Vt = 0.5 V and λ = 0. Operation at the edge of saturation is obtained when

(a) (W/L)RD = 0.5 kΩ

(b) (W/L)RD = 1.0 kΩ

(c) (W/L)RD = 1.5 kΩ

(d) (W/L)RD = 2.0 kΩ

The question was posed to me during an interview.

My question is from MOSFETs Circuits at DC topic in division MOS Field Effect Transistors (MOSFETs) of Electronic Devices & Circuits

Answer 1

Correct choice is (c) (W/L)RD = 1.5 kΩ

Explanation: Use the standard formula for edge saturation.