Optimization of FIR filters using the frequency-response masking approach

A very efficient technique for drastically reducing the number of multipliers and adders in implementing linear-phase finite impulse response filters is to use the frequency-response masking approach. A drawback in the synthesis techniques proposed up to now is that the subfilters in the overall implementation are designed separately. In order to further reduce the arithmetic complexity of these filters, a two-step optimization technique for simultaneously optimizing the subfilter is introduced. In the first step, a good suboptimal solution is found using a simple iterative algorithm. In the second step, this solution is then used as a start-up solution for further optimization carried out by using the second algorithm of Dutta and Vidyasagar (1977). An example taken from the literature is included illustrating that the number of adders and multipliers for the resulting filters are less than 80 percent compared with the earlier ones.