Question

The minority charge concentration can be represented as Q = V^2 – 33V. If the voltage being applied is now 5V, find the diffusion capacitance.

(a) 1μF

(b) 0.1μF

(c) 10μF

(d) 0.9μF

This question was addressed to me in an online quiz.

My question is based upon Diffusion Capacitance in division Diode Circuit of Analog Circuits

Answer 1

Right choice is (b) 0.1μF

To explain: Q = – \(\frac{V^{-9}}{9}\)

CD = \(\frac{dQ}{dV}\) = V^-10 = 1.024 x 10^-7

CD = 0.1μF.