Semiconductor Devices

The question tells us that the voltage gain divided by the current amplification factor ( β ) equals 4.
We know that the formula for voltage gain in a common emitter amplifier is AV=‌

β×RC

RB

, where RC is collector resistance and RB is base resistance.
So if we divide AV by β, we get:
‌

AV

β

=‌

‌ β×RC RB

β

This simplifies to:
‌

RC

RB

The question gives ‌

AV

β

=4, so:
‌

RC

RB

=4
This means the ratio of collector resistance to base resistance is 4:1.