Question

What is the approximate hybrid parameter current gain of a CB amplifier?

(a) -hfe / 1 + hfe

(b) -hfe / 1 – hfe

(c) hfe / 1 + hfe

(d) hfe / 1 – hfe

This question was addressed to me in a national level competition.

My question is taken from Approximate Hybrid Model and its use in CE, CB, CC in division Small-Signal Low-Frequency AC models of Transistors of Electronic Devices & Circuits

Answer 1

Right option is (c) hfe / 1 + hfe

Explanation: The current gain of a common base (CB) amplifier can be expressed in terms of approximate hybrid parameters. The current gain hfe is the forward transfer characteristics. The current gain of a common base amplifier is expressed as hfe / 1 + hfe.