Question

In a common-emitter transistor amplifier, the audio signal voltage across the collector is $3V$. The resistance of collector is $3k\Omega$. If current gain is $100$ and the base resistance is $2k\Omega$, the voltage and power gain of the amplifier is

• A. 15 and 200
• B. 150 and 15000
• C. 20 and 2000
• D. 200 and 1000

Answer 1

The correct option is B 150 and 15000

Given,
$V_c=3V$
$R_c=3000\Omega$
$\beta =100$

As,
$I_c=\frac{V_c}{R_C}\Rightarrow \frac{3}{3000}={10}^{-3}A$
$I_b=\frac{I_c}{\beta }\Rightarrow \frac{{10}^{-3}}{100}={10}^{-5}A$
$V_b=I_b{R}_b\Rightarrow {10}^{-5}\times 2000$$=2\times {10}^{-2}V$
voltage gain $=\frac{V_c}{V_b}=\frac{3}{2\times {10}^{-2}}=150$
Power gain $=\beta \times$ voltage gain
$=100\times 150$
$=15000$