Design of causal stable IIR perfect reconstruction filter banksusing transformation of variables

A generalisation to the design technique of Tay and Kingsbury (see IEEE Trans. Circuits Syst. II: Analog Digit. Signal Process., vol.43, no.2, p.274-79, 1996) for two-channel, causal stable IIR perfect reconstruction filter banks is presented based on transformation of variables. Previously the transformation functions used were allpass, but this yielded subband filters with a fairly large overshoot in their frequency design responses. By relaxing the requirement of using allpass transformation functions, filters with improved response (lower and no overshoot) are achievable. Several design examples are presented to show the flexibility of the design technique