Filters

Abstract

A filter is an electronic circuit that prevents the passage of signals, in a certain band of frequencies, from one circuit to another. There are four types of filter associated with the frequency band in which they operate. These are

• ⎕ low pass

• ⎕ high pass

• ⎕ band pass

• ⎕ band stop

Each filter has an ideal characteristic that cannot be achieved practically. In efforts to attain a response close to ideal, several response shapes have been obtained by experiment and have become accepted as standards. Some of these will be examined later in this chapter.