Design of FIR Partial Response Filter with Equiripple Stopband Attenuation (Class )


IEICE TRANSACTIONS (1976-1990)   Vol.E71   No.11   pp.1107-1115
Publication Date: 1988/11/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Digital Signal Processing

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Two design methods, namely method 1 and method 2, for class partial response FIR filters with equiripple stopband attenuation and low intersymbol interference (ISI) are investigated. For method 1, we design only a transmitter filter. For method 2, we design a transmitter and receiver filter pair having nearly the same amplitude response in the frequency domain. Both design methods have mainly three steps in common. First, a truncated sampled sequence of an ideal impulse response is used as an initial impulse response of the filter or filter pair in cascade. The optimum length of the sequence is examined. Second, z is transformed into such that the stopband section on the z-plane unit circle of the filter is mapped to be the entire unit circle in the -plane. Then a special all-zero function of is constructed having equiripple amplitude response along the unit circle. From this function, the filter transfer function of z with equiripple stopband attenuation is derived by inversely transforming into z. Finally, zero ISI approximation is performed with least-squares criterion, which drastically reduces ISI without significant change in the attenuation. Various characteristics of the filters designed by both methods are also illustrated.