Question

For $CE$ transistor amplifier, the audio signal voltage across the collector resistance of $2 k \Omega$ is $4\, V$. If the current amplification factor of the transistor is $100$ and the base resistance is $1 \, k\Omega$, then the input signal voltage is

• A. 10 mV
• B. 20 mV
• C. 30 mV
• D. 15 mV

Answer 1

Answer: (B)

20 mV

Answer 2

$\beta=100$
$R_{C}=2 k \Omega$
$v _{0}=4 V$
$R _{ B }=1 k \Omega$
$A =\frac{ v _{0}}{ v _{ i }}=\beta \frac{ R _{ C }}{ R _{ B }}$
$v _{ i }=\frac{ v _{0} \times R _{ B }}{\beta R _{ C }}=\frac{4 \times 10}{100 \times 2 \times 10^{3}}=20\, mV$