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The authors consider the design of multirate filterbanks for applications such as subband coding with IIR QMF (quadrature mirror filter) pairs. These offer reduced complexity and low latency at the expense of the loss of exact linear phase. In particular, consideration is given to the use of all-pass sections where linear phase is approximately achieved by being part of the objective in numerical optimisation experiments. This approach compares favourably with previous IIR based approaches. Finite wordlength design using simulated annealing shows that low coefficient wordlength may be used. This leads to efficient realisations with three-port adaptors. Using pipelining implementation, a flexible VLSI architecture is designed that can be used for a variety of subband decompositions. Layout and simulation of the design have been performed.