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Question: A common emitter amplifier is designed with NPN transistor (α = 0.99). The input impedance is 1 KΩ a...

A common emitter amplifier is designed with NPN transistor (α = 0.99). The input impedance is 1 KΩ and load is 10 KΩ. The voltage gain will be

A

9.9

B

99

C

990

D

9900

Answer

990

Explanation

Solution

Voltage gain = β × Resistance gain

β=α1α=0.99(10.99)=99\beta = \frac{\alpha}{1 - \alpha} = \frac{0.99}{(1 - 0.99)} = 99

Resistance gain =10×103103=10= \frac{10 \times 10^{3}}{10^{3}} = 10

⇒ Voltage gain = 99 × 10 = 990.