types of filters

1. Filters:-
In signal processing a filter is a device or process that removes some unwanted
components or features from a signal. Electronic filters are circuits which perform signal
processing functions, specifically to remove unwanted frequency components from the
signal, to enhance wanted ones, or both.
Electronic filters can be:
High-pass filters:-
A high-pass filter is an electronic filter that passes signals with a frequency higher than a
certain cut off frequency and attenuates signals with frequencies lower than the cut off
frequency.
Low-pass filters:-
A low-pass filter is a filter that passes signals with a frequency lower than a certain cut off
frequency and attenuates signals with frequencies higher than the cut off frequency.
Band-pass filters:-
A band-pass filter (also spelled band-pass) is a device that passes frequencies within a
certain range and rejects (attenuates) frequencies outside that range.
Band-stop filters:-
In signal processing, a band-stop filter or band-rejection filter is a filter that passes
most frequencies unaltered, but attenuates those in a specific range to very low levels. It is
the opposite of a band-pass filter.
All-pass filters:-
An all-pass filter is a signal processing filter that passes all frequencies equally in gain, but
changes the phase relationship among various frequencies. It does this by varying
its phase shift as a function of frequency. Generally, the filter is described by the frequency
at which the phase shift crosses 90°.