Modified Realization Technique for Digital Filters Derived from Analog Counterparts

Abstract

A simple realization scheme for one-dimensional and two-dimensional recursive digital filters derived from analog reference transfer functions is presented. The method is based on proper predistortion of the analog transfer function to obtain a new Hurwitz polynomial. Analog-to-digital transformations, such as the bilinear transformation, are then applied to the resulting predistorted reference transfer function to obtain the discrete version of the system. It is shown that a proper choice of the predistorting function will yield digital realizations which are free of the delay-free loops and in most cases are near minimal. To illustrate the simplicity and efficiency of the technique, examples of 1-D and 2-D cases are worked out. The proposed scheme can readily be extended to include the multi-dimensional case.