Serialization of tree structured Quadrature Mirror Filter bank

Abstract

Efficient implementations of multichannel tree-structured filter banks require sharing of the tree nodes at each stage. While there exist many implementation structures and methods of tree-structured filter banks, most of them are based on some ad hoc tricks requiring application dependent data manipulations/buffering and/or careful scheduling of process control. This paper presents a serialized QMF tree structure that shares a common 2-channel Quadrature Mirror Filter (QMF) in each tree stage. With simple and well defined regular data permutation between tree stages, it eliminates the need for data buffering and scheduling. The proposed Serial QMF Tree structure is in essence a single rate multi stage filter that is fully pipelined and retains the throughput of the original tree structure. For an M-stage tree filter bank, the complexity of the Serial QMF Tree is equivalent to that of M prototype filters. The proposed method and architecture can be extended to serialize and pipeline other decimation/interpolation tree structures such as discrete wavelet transforms and frequency domain channelizers/synthesizers.