A laser-power stabilisation loop's dominant closed-loop pole pair is at
PHYSICS · Multi-part · Fermi University Physics · Electronics, Instrumentation & Communication · Feedback, operational amplifiers and analogue signal processing · Signals, systems, control and digital signal processing
Electronics for Measurement, Ch Transfer functions, poles and the stability of a loop
Problem
A laser-power stabilisation loop's dominant closed-loop pole pair is at s=−2000±j2000s−1. Treat the closed loop as the standard second-order low-pass set by this pair, with no zero near it.
((a)) State the envelope time constant and the ringing frequency (in hertz) these poles predict for a step response.
((b)) Give f0, Q, and say whether the Bode magnitude shows a resonant peak above the low-frequency gain, with a reason.
((c)) The loop is proportional-only with a zero-frequency loop gain Tdc=25. Give the fraction of a set-point step left as steady-state error.