Question

A $n-p-n$ transistor is connected to common emitter configuration in a given amplifier. A load resistance of $800$ is connected in the collector circuit and the voltage drop across it is $0.8\, V$. If the current amplification factor is $0.96$ and the input resistance of the circuit is $192\,\Omega$, the voltage gain and the power gain of the amplifier will respectively be

• A. 3.69, 3.84
• B. 4 , 4
• C. 4, 3.69
• D. 4, 3.84

Answer 1

Answer: (D)

4, 3.84

Answer 2

Given $\alpha = 0.96$
so, $\beta = \frac{\alpha}{1- \alpha} = \frac{0.96}{0.04} \, \Rightarrow \, \beta = 24$
Voltage gain for common emitter configuration
$A_V = \beta . \frac{R_L}{R_1} = 24 \times \frac{800}{192} = 100$
Power gain for common emitter configuration
$P_V = \beta A_V = 24 \times 100 = 2400$
Voltage gain for common base configuration
$A_V = \alpha . \frac{R_L}{R_P} = 0.96 \times \frac{800}{192} = 4$
Power gain for common base configuration
$P_V = A_V \alpha = 4 \times 0.96 = 3.84$

• In the question it is asked about common emitter configuration but we got above answer for common base configuration.