Question

In a MOSFET operating in the saturation region, the channel length modulation
effect causes
(A) an increase in the gate-source capacitance
(B) a decrease in the transconductance
(C) a decrease in the unity-gain cutoff frequency
(D) a decrease in the output resistance

Answer 1

D is the perfect answer and also the current increases with drain bias

Answer 2

In a MOSFET operating in the saturation region, the channel length modulation  effect causes (D) a decrease in the output resistance

Without the channel length modulation the drain current of a MOSFET is given by,

Id = μ/2 x C(W/L)(Vgs - Vt)²

∴ dI/dV = 0

=> dV/dI = ∞

=> Rd = ∞

If we consider channel length modulation, the value of Rd will be always less than ∞ .  So, channel length modulation decreases the output resistance.