Question

Consider an abrupt PN junction. Let V0 be the built in potential of this junction and VR be the reverse bias voltage applied. If the junction capacitance Cj is 1pF for V0+VR =1V, then for V0+VR =4V what will be the value of Cj?

(a) 0.1pF

(b) 1.7pF

(c) 1pF

(d) 0.5Pf

This question was posed to me in an online quiz.

I'm obligated to ask this question of Diode Capacitances in portion Semiconductor-Diode Characteristics of Electronic Devices & Circuits

Answer 1

Correct option is (d) 0.5Pf

The explanation: We know, Cj1/ Cj2=[(V0+VR2)/(V0+VR1)]^1/2

Cj2=Cj1(1/4)^1/2=1/2 .

We get Cj2=1/2=0.5pF.