Fixed-point FIR filter design and implementation in the expanding subexpression space

This paper presents a method of combining the design and the implementation of fixed-point FIR filter coefficients into one design flow. The proposed method designs the fixed-point coefficients in an expanding subexpression space. During the design process, the implementation cost is estimated as well and it is fed back to the design routine such that the algorithm can redesign the fixed-point coefficients iteratively. Design examples show that, in many cases, we can obtain better hardware-cost- effective FIR filters than the results reported by other researchers.