Electronics and Communication Engineering - Analog Electronics - Discussion

Given:

Gain of amplifier (A) = -1000.
Feedback factor (β) = -0.1.
Gain change due to temperature (ΔA/A) = 20% = 0.2.

We know that the gain of the feedback amplifier (Af) is:
Af = A/(1 + βA).

To find the change in gain of the feedback amplifier (ΔAf/Af), we can use the formula:
ΔAf/Af = ΔA/A / (1 + βA).

Substituting the values:
ΔAf/Af = 0.2/(1 + (-0.1) × (-1000)).
ΔAf/Af = 0.2 /(1 + 100).
ΔAf/Af = 0.2 /101.
ΔAf/Af ≈ 0.00198.

To express this as a percentage:

ΔAf/Af ≈ 0.198%.

So, the change in gain of the feedback amplifier would be approximately 0.198%.

This is basically a problem relating the stability of gain of feedback amplifiers.

Given, A = -1000, B (beta) = -0.1; 1+AB = 101.

Now, given, change in amplifier gain = 20%.

We have, (dAf/Af) = (1/(1+AB))*(dA/A).

Here, dA/A = 20% = 0.2; have to find dAf/Af.

Therefore, dAf/Af = (1/101)*0.2 = 0.00198 = 0.198% = 0.2%.

Option (C) is correct. Here it is noticeable how feedback improves the stability in amplifiers. When the deviation of gain in amplifier is 20%, the distortion in the overall (feedback) amplifier circuit is only 0.2%.

Thank you.

@Arnab Bhattacharya,

Thanks for the clear explanation.

@Arnab.

Thanks for the clear explanation.

Great explanation @Arnab Bhattacharya.

Thank you for explaining the answer.

Great explanation. Thank you @Arnab.

Thank You for explaining this..

Now it's clear, thanks @Arnab.

Can it get explained clearly?