Polyphase Filter Design with Reduced Phase Non-Linearity (original) (raw)

The perfect linear phase requirement can be achieved only by direct design with an FIR filter at the expense of high filter order and hence high computational burden for the given specification. Alternatively, IIR filters can be designed with much smaller orders than their FIR counterparts, but at the expense of the non-linear phase. However, it is possible to design almost linear-phase IIR filters for a given specification of the allowed phase or group delay ripples. This paper presents an improvement to the existing algorithms for the design of almost linear–phase, arbitrary-band IIR filters and gives a different viewpoint on these methods, showing a considerable improvement in maximum ripples of the magnitude and group delay responses. The idea of decreasing the phase non-linearity of the N-path polyphase IIR filters with a combination of allpass sections of different order and coefficient polarity is presented. The effect of coefficient quantization, in view of the fixed-point i...

Almost linear-phase polyphase IIR lowpass/highpass filter approach

International Symposium on Signal Processing and Its Applications, 1999

The direct design of a linear phase FIR filter allows one perfectly linear phase, but at the expense of the high filter order, N, and consequently high computational burden for the given specification. IIR filters, however, can be designed with much smaller orders than their FIR counterparts, but at the expense of the non-linear phase. It is, however, possible to design almost linear phase IIR filters for a given specification of the allowed phase or group delay ripples. There are few approaches for the design of such filters. This paper provides an improvement on the existing algorithms and gives a different viewpoint on these design methods showing a considerable improvement in both stopband attenuation (as well as passband ripples) and maximum group delay ripples over the methods reported previously

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

The polyphase IIR N-path structure based on the Nth-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

PHASE LINEARITY IN POLYPHASE FILTERS

Polyphase structures composed of recursive filters as subsections can be made to have either approximately linear or nonlinear phase response depending on the requirements of the application. There are several ways to obtain approximately linear phase filters. In this paper, we are concemed with the phase deviation from linearity in polyphase filters composed of infinite impulse response allpass sections. A linear relationship is presented between the number of delay sections per branch and the phase deviation from linearity which allows the designer to know how many nonzero sections are needed per branch in order to obtain a certain deviation from linearity beforehand.

A Procedure for Quasi-Equiripple Linear-Phase IIR Filters Design

International Journal of Electronics and Telecommunications, 2010

A Procedure for Quasi-Equiripple Linear-Phase IIR Filters DesignThe linear-phase IIR filters are described in many cases, mainly due to distortion-free transmission of signals. One of the major problems of IIR filter design is stability, which can be obtained with suitable value of group delay τ. This paper concerns calculation of filter orderNand group delay τ in case of quasi-equiripple design of IIR filters. We propose a novel procedure for determiningNand τ values; the procedure is valid for all types of filters with arbitrary number of zeros and a few non-zero poles. Evaluation of the proposed approach as well as examples illustrating its application are provided in the paper.

Efficient Design of Half-Band IIR Filter using Polyphase Structure

IAEME PUBLICATION, 2015

In this paper, the half-band IIR filter is designed as a polyphase structure of all-pass sub-filters. The proposed design method provides desirable properties of the half-band IIR filter to achieve the efficient design. The complexity of the designed filter is considered in terms of number of adders. In order to keep the complexity of the design method as low as possible, we are neglecting the less sensitive coefficients of the designed filter such that there is a trade-off between efficiency and complexity. Simulation results reveals that the proposed method provides a half-band filter with less complexity and smaller filter order. The results affirm that with the removal of less sensitive coefficient, the designed half-band filter approaches the ideal half-band filter.

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