Question

Two identical FETs, each characterized by the parameters g_m and r_d are connected in parallel .The composite FET is then characterized by the parameters_____________

(a) gm/2 and 2rd

(b) gm/2 and 2rd

(c) 2gm and rd/2

(d) 2gm and rd/2

The question was posed to me during an interview.

My question is taken from The Junction Field-Effect Transistor in division Field-Effect Transistors of Electronic Devices & Circuits

Answer 1

The correct choice is (c) 2gm and rd/2

Best explanation: By converting FET into ac equivalent circuits and connecting them in parallel,

gn = 2gm  and  rn = rd/2.