Question

An n-p-n transistor power amplifier in C-B configuration gives
A voltage amplification only.
B current amplification only.
C both current and voltage amplification.
D only power gain of unity

Answer 1

The input signal is applied between the emitter and base terminals while the corresponding output signal is taken across the collector and base terminals. Thus, the base terminal of a transistor is common for both input and output terminals and hence it is named as common base configuration. And by using the current gain in PNP transistor formula the solution can be determined.

Complete step by step answer:
The power gain PG of an n-p-n transistor in CB configuration is given by:
$PG = CG \times VG$
Here, CG is the current gain and VG is the voltage gain.

Therefore, the correct option is (C).

Additional Information:- An input characteristic is a curve between base current and base emitter voltage at constant collector emitter voltage. -An output characteristic is the curve between collector current and collector-emitter voltage at constant base current. -An amplifier is a device that increases the amplitude of an AC signal and this process is called amplification.

Note: Current gain in the common emitter circuit is obtained from the base and the collector circuit currents. Because a very small change in base current produces a large change in collector current, the current gain is always greater than unity.