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FILTER CIRCUITS are designed to smooth, or filter, the ripple voltage present on the pulsating dc
output of the rectifier. This is done by an electrical device that has the ability to store energy and to
release the stored energy.
CAPACITANCE FILTERS are nothing more than large capacitors placed across the output of the
rectifier section. Because of the large size of the capacitors, fast charge paths, and slow discharge paths,
the capacitor will charge to average value, which will keep the pulsating dc output from reaching zero
volts.
INDUCTOR FILTERS use an inductor called a choke to filter the pulsating dc input. Because of
the impedance offered to circuit current, the output of the filter is at a lower amplitude than the input.
