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In a negative feedback amplifier, the gain without feedback is 100, feed back ratio is 1..25 and input voltage is 50mA. Calculate (i) gain with feedback (ii) feedback factor (iii) output voltage (iv) feedback voltage (v) new input voltage so that output voltage with feedback equals the output voltage without feedback |
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Answer» Solution :i) Gain with FEEDBACK `A_(f)=(A)/(1+beta)=(100)/(1+1//25xx100)=20` ii) `beta=(1)/(25)` iii) OUTPUT voltage `V_(0)=A_(f)V_(s)=20xx50mV="1 volt"` iv) Feedback voltage `betaV_(0)=(1)/(25)xx1="0.01 volt"` v) New increased INPUT voltage `V_(i)=V_(i)(1+beta)` `=50(1+(1)/(25)XX100)=250mV` |
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