In this paper we address design and properties of an oversampled non-uniform DFT filter bank derived by an allpass frequency transform from its uniform version. The novel synthesis bank utilizes only stable FIR filters, which can be designed via closed-form expressions. The overall analysis-synthesis system leads to a near-perfect-reconstruction solution, where the phase compensation error can be made arbitrarily small at the expense of additional system delay. Furthermore, we also address the case of different sub-sampling factors in the subbands. The filter bank design is carried out by utilizing a lifting factorization for the prototypes, which has the advantage that the overall system delay can be controlled in an efficient way.

We describe a novel approach for the design of near-perfect-reconstruction mixed FIR-/allpass-based quadrature mirror filter banks. The design is carried out in the polyphase domain, where FIR filters, obtained via simple closed-form expressions, are employed for compensating the nonlinear phase introduced by the allpass filters. Starting from a generalized two-band structure, we introduce three different types of analysis-synthesis banks based on the same design principle. In all systems the remaining linear and phase distortions can be made arbitrarily small at the expense of additional system delay. Simultaneously, aliasing can be minimized, or completely canceled if further delay can be tolerated.

In this paper we address a maximally decimated IIR DFT filter bank, where all polyphase components are replaced by all pass filters. Generally a perfect reconstruction (PR) solution leads to a synthesis filter bank with unstable subband filters. As a novelty we show that by using closed form FIR phase compensation filters as polyphase components in the synthesis filter bank we obtain a stable near-PR analysis-synthesis system. Furthermore, the remaining linear and aliasing distortions only depend on the overall system delay and can be made arbitrarily small.

In this contribution we discuss an oversampled non-uniform DFT filter bank, which is derived by allpass frequency transformations from its uniform version. Here, a perfectreconstruction (PR) solution generally requires a non-stable synthesis filter bank. As a new result we show that by alleviating the PR conditions it is possible to construct a stable synthesis system, where the subband filters are of FIR type. The delay of the resulting near-PR system can be efficiently controlled by a factorization of the analysis and synthesis filter bank into lifting steps.