Voltage gain of an amplifier with 10 % positive feedback is 10. The voltage gain without feedback is
1. 5
2. 0.5
3. 0.05
4. 50

Asked by rajeshtitu | 19th Jul, 2016, 09:13: PM

Expert Answer:

begin mathsize 14px style The space voltage space gain space without space feedback space is space straight A subscript straight v.
The space voltage space gain space with space feedback space is space straight A subscript vf.
When space positive space feedback space is space given comma space we space have
straight A subscript vf equals fraction numerator straight A subscript straight v over denominator 1 minus βA subscript straight v end fraction
straight beta equals 10 percent sign equals 0.1
therefore 10 equals fraction numerator straight A subscript straight v over denominator 1 minus 0.1 straight A subscript straight v end fraction
therefore 10 minus straight A subscript straight v equals straight A subscript straight v
therefore 2 straight A subscript straight v equals 10
therefore straight A subscript straight v equals 5 end style

Answered by Romal Bhansali | 20th Jul, 2016, 11:46: AM