Question

The configuration in which current gain of transistor amplifier is lowest is ___________

(a) common collector

(b) common base

(c) common emitter

(d) common emitter & base

I have been asked this question by my school teacher while I was bunking the class.

The above asked question is from Comparison of Transistor Amplifier topic in section Small-Signal Low-Frequency AC models of Transistors of Electronic Devices & Circuits

Answer 1

Correct choice is (b) common base

For explanation: In Common base configuration, the input impedance is very low; While offering a high output impedance. Although the voltage is high, the current gain is low and the overall power gain is also low when compared to the other transistor configurations available. Thus, there is no current amplification because of unity current gain.