A closed-form transfer function of low delay bandpass FIR filters with flat characteristics in the passband and the transmission zeros in the stopband

摘要

FIR digital filters are always stable and practically important in the pulse communication and the high-speed data transmission. Since the coefficients of the transfer function of FIR filters become symmetrical in the case of realization of complete linear phase characteristics, the groupdelay requires a half filter length. In order to obtain a filter with the steep characteristics, the large filter length is needed. So, the groupdelay of the filter increases. Thus, it is very problem on the real-time processing. Recently, several design methods of low delay FIR filters have been proposed. However, in the designing low delay bandpass FIR filters, a design method using successive projection method is only proposed. In this paper, we propose a closed-form transfer function of low delay bandpass FIR filters with flat characteristics in the passband and the transmission zeros in the stopband. The proposed filter has the specified flatness of amplitude characteristics and groupdelay at an arbitrary frequency in the passband and the specified transmission zeros in the stopband. Since the proposed transfer function is a closed-form expression, the proposed method is very simple.