Realization of multirate digital filters with powers‐of‐two coefficients

Abstract

With a view to reducing the amount of hardware in the lowpass filter (LPF), bandpass filter (BPF), and band‐elimination filter (BEF) processing important in digital signal processing, this paper presents a method for configuration of the multirate digital filters with powers‐of‐two coefficients only. The proposed filters are constructed with the sampling rate increaser, the reference LPF and the sampling rate decreaser. The reference LPF consists of the stopband‐forming filter and the pass‐band compensating filter. The stopband‐forming filter consists of a cascade of RRSs while the linear phase FIR or IIR configuration is used for the passband‐compensating filter. First, a method of configuration is presented for the reference LPF based on the sampling rate increaser with powers‐of‐two coefficients. Next, it is shown that the multirate LPF, HPF (high‐pass filter), BPF and BEF with an arbitrary cutoff frequency can be constructed easily from the reference LPF. The present method is particularly effective for narrowband LPF and HPF. Since no multiplier is used, they have zero coefficient sensitivity. It is shown by means of a design example that the present method is effective in reducing the amount of hardware.