The ripple in the output of a rectifier circuit with capacitor filter is due to the discharging of the capacitor as the voltage decrease from the peak value. To reduce the ripples, the time for the capacitor to discharge should be increased with respect to the time period of the rectified wave. There are three ways to do this,

1. The time constant of the capacitor should be increased. The time constant of the capacitor is given by,

Therefore, the capacitance of the capacitor should be increased.

2. From the above equation, to increase the time constant the load resistance can also be increased.

3. Increasing the frequency of the input wave would reduce the time period of the wave in comparison to the capacitor discharge time and thus would decrease the ripples.