The input resistance of a common – emitter amplifier is 2 kΩ and AC current gain is 20. If the load resistor used in 5 kΩ, then calculate the transconductance of the transistor used:

$0.01Ω^{-1}$

$g_m=\frac{A_V}{R_L}$

where, $A_V$ = voltage gain = $β_{ac}$ × resistance gain

and $R_L$ = load resistance

$∴A_V=20×\frac{5}{2}=50$

$∴g_m=\frac{50}{5×10^3}=0.01Ω^{-1}$