Question 5
- State two effects each of: (a) positive feedback; (b) negative feedback.
Figure 3 below is a summing op-amp circuit.
- In Figure 3, calculate the value of the output voltage (Vout)
Observation
The expected answers were:
(a) (i) effects of positive feedback:
(a) Increases gain
(b) Increases distortion
(c) Decreases bandwidth
(ii) Effects of negative feedback:
(a) Decreases gain
(b) Decreases distortion
(c) Increases bandwidth
(b)
= -(20 + 20)
= - 40V
The question was on Circuit Analysis. It was unpopular with the candidates. As reported, not many of the candidates that attempted it understood the requirements of the question.