A series-pass regulator's error amplifier has open-loop voltage gain (measured with…

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

Electronics for Measurement, Ch Power supplies: holding a rail steady

Problem

A series-pass regulator's error amplifier has open-loop voltage gain

A_v = 16.0

(measured with the load removed) and a feedback divider

\beta = 0.379

. With the loop broken (the pass transistor's base held fixed), the regulator's open-loop output resistance is

3.2\,\Omega

. ((a)) Predict the regulator's output resistance. ((b)) A

250\,\mathrm{mA}

load step is then applied on the bench and the output is observed to sag by

95\,\mathrm{mV}

. Is this consistent with the prediction, and what output resistance does the measurement imply?

Browse the problem library