Introduction to Digital Filters

The purpose of this paper is to provide an introduction to the use of digital filters. Their capabilities and limitations are discussed, as well as application requirements as direct replacements for conventional active or passive filters in real-time situations. Basic operating principles are described, and amplitude and phase characteristics are illustrated. The technique offers many advantages among which are very accurate drift-free operation, ease in changing filter characteristics, and small physical size. In addition, a linear phase characteristic can readily be obtained with some types of digital filters. A design example of a linear phase low-pass filter is included.