A technique for reduction of uncertain FIR filters

In this paper, an algorithm for designing an IIR filter from a given uncertain FIR filter is proposed. An approach to properly assign the uncertainties in the FIR polynomial transfer function, to two parts of its factorization, is cleverly used. The resulting approximated IIR filter is inherently stable. The method proposed is in the time domain, based on the LSI approximation. An example of reducing a 16/sup th/ order interval FIR filter to a 4/sup th/ order numerator order over a 2/sup nd/ order denominator order IIR filter is presented to illustrate the design method.