One structure for wide-bandwidth and high-resolution fractional delay filter

This paper presents one structure for wide-bandwidth and high-resolution FIR fractional delay filters (FDF) with a small number of multipliers per output sample (MPS) and small coefficient computing time. The proposed structure is a modification of the model proposed by J. Vesma et al. (Proc. IEEE Int. Symp. Circuits and Systems, Hong Kong, pp. 2256-2259, Jun. 1997). Instead of the direct use of the frequency domain design, we use the time domain structure proposed by N.P. Murphy et al. (Electronics letters, vol. 30, no. 20, pp. 1658-1659, Sep. 1994). The frequency domain design is made by a least square approximation of each branch filter C_i(z) with an l^th order differentiator, but only up to half of the Nyquist frequency. Several design examples confirm that the modified structure has smaller magnitude response ripples and flatter group delay than the original one.