An automatic design procedure of IIR digital filters from an analog low-pass filter

Abstract

IIR digital filters are generally designed from an analog low-pass filter by any combination of the bilinear transformation, frequency transformation for analog filters and that for IIR digital filters. But the direct application of these transformations yields a complicated formula of the target transfer function, which has to be reduced by hand computation into the form of a rational polynomial. This hand computation will be replaced by an automatic procedure if the relation between the coefficients of the transfer functions is formulated. This paper derives the explicit formulae which connect those coefficients by matrices.