hi all i got this operational amplifer question was wondering if anyone can help out(adsbygoogle = window.adsbygoogle || []).push({});

1. a feedback amplifier has a closed loop gain of 100, and the negative feedback is 0.8% of the output signal. the opamp has an open loop gain which is considerable less then the ideal value of infinity.

a) what is the open loop gain

b) what would the closed loop gain be if the opamp had an infinite open loop gain

ok for this question i assume this is an inverting amplifier so i know these formulas

A (gain for closed loop) = Vout/ Vin = -RF / Rin

A (gain for open loop) = Vout / (V1 - v2)

i am guessing these steps hope it is right

we know closed loop gain = 100 hence

100 = -RF / RIN

and i know -RF=0.8/100 * Vout

i know RF=-100 and RIn=1

100 = (0.8/100) * Vout

Vout = 12500 V

Vin = 125 V

so open loop gain = 12500 / (125 - 12500)

= -1.01 ???

b) no idea about this, would it be 0?

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# Homework Help: Using maths - Amplifiers

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