Ripple factor (choke)

Description

For the root mean square value of the ripple voltage, the calculation is more involved as the shape of the ripple waveform has a bearing on the result. Assuming a sawtooth waveform is a similar assumption to the ones to calculate ripple voltage (see Ripple voltage). An approach to reducing ripple is to use a series choke. A choke has a filtering action and consequently produces a smoother waveform with less high-order harmonics. Against this, the DC output is close to the average input voltage as opposed to the higher voltage with the reservoir capacitor which is close to the peak input voltage. With suitable approximations, the ripple factor is given by the shown formula.