Acceleration-Invariant Approximation Method for Recursive Digital Filters

摘要

This document describes a procedure for designing recursive digital filters from continuous-time filters when the ratio of the sampling frequency to the pole frequency is small. The discrete-time transfer function of digital filters obtained by this method, called the acceleration-invariant transformation, has been derived from the partial fraction expansion of the continuous-time transfer function. An error function between the digital and analog transfer functions has also been deduced. Finally, the performance of the proposed method is demonstrated by plotting the frequency response of high-order Butterworth and elliptic filters. (Author)