Question

For a common-emitter amplifier, the voltage gain is 40. Its input and output impedances are 100Ω and 400Ω, respectively. The power gain of the CE amplifier will be ______.

Options

• 450

• 400

• 300

• 500

Answer 1

For a common-emitter amplifier, the voltage gain is 40. Its input and output impedances are 100Ω and 400Ω, respectively. The power gain of the CE amplifier will be 400.

Explanation:

Given, voltage gain = 40, R_in = 100Ω, R_out = 400Ω

Since, voltage gain = `beta((R_"out")/R_"in")`

⇒ β = Voltage gain × `R_"in"/R_"out" = 40 xx 100/400 = 10`

Power gain = β × voltage gain = 10 × 40 = 400