DESIGN OF FIXED-POINT STATE-SPACE DIGITAL-FILTERS WITH LOW ROUND-OFF NOISE

A simple method is described for the design of fixed-point recursive d igital filters with low round-off noise. The method is based on reduci ng to zero as many as possible of the coefficients of the filter state matrices. An optimization procedure is used to get the optimum value of linear transformation that minimizes the total output round-off noi se power. Compared with the existing approaches, this method is charac terized by its computational simplicity, very low output round-off noi se (if not the lowest possible) and low coefficient sensitivity. The s tructure of the proposed technique is modular, which makes it suitable for VLSI implementation. The technique is then employed to obtain a r educed-order low-round-off-noise filter with characteristics equivalen t to some desired FIR specifications. Illustrative examples are given to verify these advantages.