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If an amplifier with gain of 1000 and feedback of β = – 0·1 had a gain change of 20% due to temperature, the change in gain of the feedback amplifier would be—
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- 10%
- 5%
- 0·2%
- 0·01%
Correct Option: C
Given,
A = 1000
β = – 0·1
| = 20% = 0·20 | A |
| = ? | Af |
| We know that Af = | …(i) | 1 + Aβ |
Where, Af = Gain after feedback
A = Gain
β = Feedback factor
| Now, | = | …(ii) | dA | (1 + Aβ)2 |
From equation (i) & (ii)
| = | Af | 1 + Aβ |
| or | = | Af | 1 + 1000 × (0·1) |
| = | ≈ 0·2% | 101 |
Hence alternative (C) is the correct choice.