The design of arbitrary-band multi-path polyphase IIR filters

The polyphase IIR N-path structure based on the N^th-order all-passes is very attractive for high quality fractional-band filters, as high attenuation and small passband ripples can be achieved for much less coefficients than other filter structures. However, its general form suffers from spikes in the stopband independent from the coefficient values. The paper presents alternative ways to those found in literature of designing spike-less filters with minimum compromise to the filter performance and complexity