Digital all-pole filter approximations

Two different approximation methods are considered in this paper-the bilinear transformation, and the all-pole approach. Each method has its advantages, but it will be seen that the all-pole design gives superior selectivity, for a given amount of calculations per input cycle. The bilinear transformation method takes advantage of analogue filter designs, which are mapped into the digital domain. The all-pole digital filters is based on a new mapping between the z plane and the w plane