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


IEICE TRANSACTIONS (1976-1990)   Vol.E71   No.5   pp.485-492
Publication Date: 1988/05/25
Online ISSN: 
Print ISSN: 0000-0000
Type of Manuscript: PAPER
Category: Digital Signal Processing

Full Text: PDF>>
Buy this Article

A method of designing digital FIR transmitter and receiver filter pairs for classes and partial response systems is presented. The truncated ideal impulse response of a specified class is used as an initial response of the filter pair in cascade. For class I filter, the impulse response has an even symmetry, then its transfer function is a linear phase lowpass function of case 1 or case 2. Therefore, the passband zeros occur in mirror image quadruplet (and doublet) and the stopband zeros occur on the unit circle. The initial stopband attenuation slopes gradually up as frequency increases. To get an equiripple stopband attenuation for both filters, the passband zeros inside and outside the unit circle are assigned to transmitter and receiver filters respectively, then the stopband zeros of each filter are redetermined. Both filters form a matched filter pair. Next, the passband zeros of the filter pair are adjusted to give minimum intersymbol interference (ISI) in the overall response. For class filter, the impulse response has an odd symmetry and its transfer function is a linear phase lowpass function of case 3. In this case, the filter pair are designed to have equiripple and nearly the same stopband attenuation. Zero ISI approximation is performed similarly. Two design examples are shown. One is a 57th order class I filter pair having 0.05% ISI. The other is 61st order transmitter and 57th order receiver class filter pair whose ISI is 0.2%.