Question

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 1

Answer: (C)

990

Answer 2

Voltage gain = β × Resistance gain

$\beta = \frac{\alpha}{1 - \alpha} = \frac{0.99}{(1 - 0.99)} = 99$

Resistance gain $= \frac{10 \times 10^{3}}{10^{3}} = 10$

⇒ Voltage gain = 99 × 10 = 990.