Design of perfect-reconstruction nonuniform filter banks with linear-phase property

This paper proposes a new method for designing nonuniform filter banks (NUFBs) with perfect-reconstruction (PR) and linear-phase (LP) properties. It is based on the recombination structure, where the outputs of the analysis filters in a uniform original filter bank (FB) are combined by the synthesis bank of recombination FBs. New matching conditions on the original and recombination FBs for the PR NUFBs to possess good frequency characteristics are derived. This simplifies the design of the PR LP RNUFBs to those of a set of appropriate PR LP uniform FBs, which greatly reduce the design complexity. The effectiveness of the proposed method is illustrated by the design of several PR LP RNUFBs with sampling factors (2/3, 1/3) and (1/3, 2/3¹).