A Weighted Least Squares Approach to the Design of FIR Filters Synthesized Using the Modified Frequency Response Masking Structure

Abstract—This paper presents an application of the weighted least squares (WLS) method to the design of sharp linear phase finite-impulse response (FIR) digital filters synthesized using a modified frequency-response masking (FRM) structure. In our approach, the original minimax design problem is converted into a WLS problem. The WLS problem is highly nonlinear with respect to the coefficients of the filter. However, it can be decomposed into four linear least squares (LS) problems, each of which can be solved analytically. The design problem is then solved iteratively by using an alternating variable approach. The effectiveness of the method is demonstrated through solving a low-pass linear phase sharp FIR digital filter example. Index Terms—Frequency-response masking (FRM), minimax error, weighted least squares (WLS), alternating variable ap-proach. I