Question

A transistor having α = 0.90 is used in a common base amplifier. If the load resistance is 5.0 kΩ and the dynamic resistance of the emitter junction is 50 Ω, then calculate the voltage gain.

(a) 50

(b) 100

(c) 70

(d) 90

I have been asked this question in semester exam.

The question is from Semiconductor Electronics in division Semiconductor Electronics : Materials, Devices and Simple Circuits of Physics – Class 12

Answer 1

Correct answer is (d) 90

Explanation: The expression of voltage gain is as follows:

AV=\(\frac {αR_L}{R_e}\)

Given: α = 0.90, RL = 5.0 kΩ = 5000 Ω, Re = 50 Ω

AV=\(\frac {0.90×5000}{50}\)

AV = 90