A comparative study of finite word length coefficient optimization of FIR digital filters

The accuracy of a real-time digital filter frequency response is affected by the finite word length (FWL) constraint of coefficients used in its implementation. In this paper, we consider the FWL problem in regard to the finite impulse response (FIR) digital filters. Some theoretical issues and statistical error bound conditions of the maximum deviation between the exact and the approximate magnitude responses are also considered. We use realvalued genetic algorithms (GA) as an optimisation tool and derive results for the maximum error bounds and error deviation due to FWL effects for a number of design examples. Finally, a comparison is drawn between the simply rounded, the GA optimised, integer programming and the simple hill climber methods.