IIR partial response digital filter design with equiripple stopband attenuation (class I)

The design of infinite impulse response (IIR) digital transmitter and receiver filters of class I is described. The filters are designed to be quasi-matched; each has a maximally flat delay polynomial as the denominator. Each filter is designed to have an equiripple stopband attenuation as well as low, uncontrolled intersymbol interference (ISI) when cascaded. In order to get low ISI and high stopband attenuation, it is necessary for the band-edge frequency to be slightly larger than the ideal value. A brief comparison with finite impulse response filter design is made. By IIR design, the filter order and group delay are reduced about 20% and 30% respectively, but the ISI is somewhat increased.<
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