Ripple noise

In rectifier and smoothing circuits of power supply equipment, the combined value of the small AC voltage that appears superimposed on the DC voltage as ripple and high-frequency noise. It consists of the AC component that could not be removed by the low-pass filter of the rectifier and smoothing circuit, with additional high-frequency noise components other than the input sine wave. As with ripple, it is expressed as one cycle from one waveform peak to the next.