Ripple

In rectifying and smoothing circuits such as those found in power supply equipment, ripple is a small AC voltage superimposed on the DC voltage. It synchronizes with the input frequency and switching frequency, representing the AC component that could not be removed by a low-pass filter. It is expressed in one cycle from the peak of the waveform to the next peak. Minimal ripple is required in rectifying and smoothing circuits, and the ripple content rate is an index that represents its accuracy. If the effective value of the ripple voltage is ΔVac and the average value of the DC output voltage is Vdc, the ripple content rate γ is expressed by the following formula.

Γ = (ΔVac / Vdc) × 100 (%)