A choke used to filter ripple in a bench power supply is modelled as an ideal inductor
PHYSICS · Multi-part · Fermi University Physics · Electricity, Magnetism & Electromagnetism · Electronics, Instrumentation & Communication · Circuit foundations and passive networks
Electronics for Measurement, Ch Phasors, impedance and the frequency response
Problem
A choke used to filter ripple in a bench power supply is modelled as an ideal inductor L=19.1mH, its winding resistance neglected, feeding a separate load resistor R=120Ω. A 5.0kHz ripple voltage (an ideal sinusoidal source) drives this series combination, and the filtered signal is taken as the phasor voltage across the load R, with ground at the far end of R. A trap is then connected across the load, from that filtered node to ground: a series branch of an inductor L2=5.0mH, a capacitor C2=200nF, and the coil's own winding resistance R2=8.0Ω.
((a)) Without the trap, find the corner frequency of the choke stage and the magnitude and phase of its frequency response at 5.0kHz.
((b)) Find the resonant frequency f0, the quality factor Q, and the half-power bandwidth of the trap branch on its own.
((c)) With the trap connected, find the magnitude of the response at 5.0kHz, and the factor by which the trap reduces the ripple at the node.