Question

An RC coupled amplifier has a mid-frequency gain of 200 and a frequency response from 100 Hz to 20 kHz. A negative feedback network with $\beta =0.02$ is incorporated into amplifier circuit, then the new bandwidth of the amplifier is approximately equal to

• A. 50 kHz
• B. 120 kHz
• C. 100 kHz
• D. 50 kHz

Answer 1

The correct option is C 100 kHz

$D=(1+A\beta )=1+200\times 0.02=5$
$\therefore F_{LF}=\frac{F_L}{1+A\beta }=\frac{100}{5}=20Hz$
$F_{HP}=f_H(1+A\beta )=20\times {10}^3\times 5=100kHz\therefore BW=f_{HF}-f_{LP}-f_{HP}=100kHz$