Question

If 1/h12 = 4, for a C.E. stage- what is the value of the base to collector capacitance, after Miller multiplication, at the input side?

(a) 4Cµ

(b) 5Cµ

(c) 6Cµ

(d) 1.1Cµ

This question was posed to me by my college director while I was bunking the class.

This intriguing question comes from Effect of Various Capacitors on Frequency Response in chapter Transistor Frequency Response of Analog Circuits

Answer 1

Correct option is (c) 6Cµ

To explain I would say: The capacitor, Cµ, gets multiplied by a factor of (1 + Av), at the input side of a C.E. stage. 1/h12 is equal to Av since h12 is the reverse voltage amplification factor. Hence, the final value becomes 5Cµ.