A series-pass regulator has an error amplifier with open-loop voltage gain and a…
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 has an error amplifier with open-loop voltage gain Av=6.5 and a feedback divider β=0.694. With the load connected and the loop broken (the pass transistor's base held fixed), the regulator's output would show 0.85V peak-to-peak of ripple.
((a)) Predict the residual ripple at the regulator's output.
((b)) A bench measurement of the finished regulator gives 165mV peak-to-peak at the output. Is this consistent with the prediction, and, if there is a difference, what does it imply about the loop gain actually present on the bench?