Extensions of the Pade-approximant technique for the design of recursive digital filters

A closed-form solution to the problem of synthesizing recursive filters with specified gain and phase characteristics is presented. The method is shown to be numerically well conditioned, and to result in BIBO stable realizations. By means of a free design parameter, the filter response can be modified according to given criteria in a particular application. Examples indicate that the method yields, with a standard setting of the free parameter, designs very close to optimal in terms of frequency-domain performance.