Ripple

In rectification and smoothing circuits such as those in power supply equipment, it is a small AC voltage that appears superimposed on the DC voltage. It is synchronized with the input frequency and the switching frequency, and represents the AC component that could not be removed by a low-pass filter. It is defined as one cycle from the peak of the waveform to the next peak. In rectification and smoothing circuits, a low ripple is desirable. As an indicator of the precision, the ripple content ratio is used. If the effective value of the ripple voltage is ΔVac and the average value of the DC output voltage is Vdc, the ripple content ratio γ is expressed with the following formula.

Γ = (ΔVac/Vdc)×100(%)