q the gain of an amplifier without feedback is

Question

Q. The gain of an amplifier without feedback is 100 and the gain of an amplifier with feedback is 200. Calculate the feedback fraction.

Solution : Voltage gain after feedback,

A_f = A / 1 - Aβ

200 = 100 / 1 - 100 β

2 = 1 / 1 - 100 β

2 - 200 β = 1                           (that is) 200 β = 1

β = 1 /200 = 0.005