Question

The input signal given to a CE amplifier having a voltage gain of $150$ is $v_{i}=2 \cos \left(15 t+\frac{\pi}{3}\right)$ The corresponding output signal will be

• A. $2 \cos \left(15 t+\frac{5 \pi}{6}\right)$
• B. $300 \cos \left(15 t+\frac{4 \pi}{3}\right)$
• C. $300 \cos \left(15 t+\frac{\pi}{3}\right)$
• D. $75 \cos \left(15 t+\frac{2 \pi}{3}\right)$

Answer 1

Answer: (B)

Here,
Input signal, $v_{1}=2 \cos \left(15 t+\frac{\pi}{3}\right)$
and voltage gain, $A_{v}=150$
As $A_{v}=\frac{V_{0}}{V_{i}}$
$\therefore$ Output signal, $V_{0}=A_{v} V_{i}$
Since CE amplifier gives a phase difference of $\pi\left(=180^{\circ}\right)$ between input and output signals.
$\therefore V_{0}=150\left[2 \cos \left(15 t+\frac{\pi}{3}+\pi\right)\right]$
$=300 \cos \left(15 t+\frac{4 \pi}{3}\right)$