For a common-emitter amplifier, the voltage gain is 40 . Its input and output impedances are $100 \Omega$…
For a common-emitter amplifier, the voltage gain is 40 . Its input and output impedances are $100 \Omega$ and $400 \Omega$, respectively. The power gain of the $\mathrm{CE}$ amplifier will be
450
400
300
500
Solution
Power gain $=($ voltage gain $) \times($ current gain $)$
$\begin{aligned}
& \text { Current gain }=\frac{\text { output current }}{\text { Input current }}=\frac{\frac{\mathrm{V}_0}{\mathrm{z}_0}}{\frac{\mathrm{V}_{\mathrm{i}}}{\mathrm{z}_{\mathrm{i}}}} \\
& =\frac{\mathrm{V}_0}{\mathrm{~V}_{\mathrm{i}}} \cdot \frac{\mathrm{z}_{\mathrm{i}}}{\mathrm{z}_0}=\frac{40 \times 100}{400}=10
\end{aligned}$
Power gain $=40 \times 10=400$