Find (i) voltage gain with feedback (ii) value of feedback fraction m vВ . An amplifier has an open-loop gain Av = 100,000. This shows that negative feedback provides voltage gain stability. However, when negative feedback is applied, the change in gain (4.7%) is much less. Note that without negative feedback, the change in gain is 20%. If, due to ageing of components, the gain without feedback falls by 20%, calculate the percentage fall in gain with feedback. Calculate the fraction of the output fed back. If a negative feedback is applied, the gain is reduced to 100. An amplifier has a voltage gain of 500 without feedback.

If m vВ = 0.1 and AОЅ = 100, calculate the percentage change in the gain of the system if AОЅ falls 6 db due to ageing. Q6.В An amplifier has a voltage amplification Av and a fraction m vВ of its output is fedback in opposition to the input. If due to ageing, the amplifier gain falls to 40, find the percentage reduction in stage gain (i) without feedback and (ii) with negative feedback. The gain of an amplifier without feedback is 50 whereas with negative voltage feedback, it falls to 25. Calculate (i) gain without feedback (ii) feedback fraction m vВ . When feedback is removed, it requires 0.25 V input for the same output. With a negative voltage feedback, an amplifier gives an output of 10 V with an input of 0.5 V.

Input impedence circuit maker 2000