Question

How the current gain of a common base transistor amplifier expressed in terms of transistor hybrid parameters?

(a) -hfb / (1 + ZL × hob)

(b) hfb / (1 + ZL × hob)

(c) -hfb / (1 + ZL × hrb)

(d) hfb / (1 + ZL × hrb)

I have been asked this question in an international level competition.

This question is from Analysis of Transistor Amplifier Circuit using h-parameters in section Small-Signal Low-Frequency AC models of Transistors of Electronic Devices & Circuits

Answer 1

The correct option is (a) -hfb / (1 + ZL × hob)

Easy explanation: The current gain of a transistor amplifier circuit is expressed as -I2 / I1. This can be expressed in terms of transistor hybrid parameters. The current gain of a common base transistor amplifier in terms of hybrid parameters is expressed as -hfb / (1 + ZL × hob), where ZL is the load impedance.