Capacitor Input or π Filter and R-C Filter

Definition: A filter is a device or process that removes some unwanted components or features from a signal.

Rectifier filter is an electronic circuit that removes ripple or unwanted AC signal components from the output of a Rectifier.

We have already discussed about series inductor filter and shunt capacitor filter in my previous post. Practical filter circuits are derived by combining these two type of filter. One of the most commonly used combinations are capacitor input or π filter. 

Capacitor input filter consists of shunt capacitor C1 at the input followed by series inductor L and shunt capacitor C2 across the load. The later (series inductor L and shunt capacitor C2 across the load) makes the L Section Filter. I have already discussed about L Section Filter in my previous post. Major part of filtering is accomplished by  the input capacitor C1. Most of the remaining ripple is removed by the L Section Filter consisting of choke L and capacitor C2. 

The structure of this filter is same as π filter. Only difference is L in π filter is replaced here by R. R is kept much larger than C2. So the ripples are dropped across R instead of across the load resistor.

For more details on Capacitor input or π filter, please visit: Capacitor input or π filter. 
For more details on R-C filter, please visit: R-C filter. 
For more details on rectifier filter, please visit: Rectifier Filter

For more details on various electronics circuit, please visit: It’s All About Electronics.

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