An inverting amplifier is built with an operational amplifier of open-loop DC gain

PHYSICS · Multi-part · Fermi University Physics · Electronics, Instrumentation & Communication · Feedback, operational amplifiers and analogue signal processing · Feedback, operational amplifiers and analogue signal processing

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Problem

An inverting amplifier is built with an operational amplifier of open-loop DC gain A0=1×105A_0 = 1\times10^5, input resistance Rid=1 MΩR_{\rm id} = 1\,\mathrm{M}\Omega, output resistance Ro=100 ΩR_o = 100\,\Omega, and one dominant open-loop pole at fp=8 Hzf_p = 8\,\mathrm{Hz}. The resistors are R1=500 ΩR_1 = 500\,\Omega (from the source to the inverting input) and R2=10 kΩR_2 = 10\,\mathrm{k}\Omega (from the inverting input to the output); the output drives a load RL=2 kΩR_L = 2\,\mathrm{k}\Omega. ((a)) Find the return ratio TT of the controlled source AvdAv_d. ((b)) Find the direct transmission dd (the gain from source to output with the controlled source set to zero), and hence the exact closed-loop gain ACLA_{\rm CL}. ((c)) Treating the open-loop response as a single pole, find the frequency of the closed-loop pole.

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