Trying to find the right answer to this..

Wave Optics

Question

The gain of common-emitter amplifier is given by A_V= – g_mR_L. If R_L is increasing indefinitely, will the gain of the amplifier also increase indefinitely? Explain.

Answer

Gain of the common-emitter amplifier is given by,

A_V= – g_mR_{L ......} (1)

No, if the load resistance is increased indefinitely, the output current will become zero. Hence, the voltage gain will be zero. Therefore, there will be 0 gain in the amplifier.

In equation (1) g_m is called transconductance and is equal to current gain per unit input resistance.