Ripple

In rectifier-smoothing circuits such as those used in power supply equipment, it is a small AC voltage that appears superimposed on the DC voltage, synchronized with the input frequency and switching frequency, and represents the AC component that could not be removed by a low-pass filter. It is expressed as one cycle from one waveform peak to the next. In rectifier-smoothing circuits, low ripple is required, and the ripple factor is used as an index to indicate its accuracy. If the RMS value of the ripple voltage is ΔVac and the average value of the DC output voltage is Vdc, the ripple factor γ is expressed by the following formula.

Γ=(ΔVac/Vdc)×100(%)