  This paper presents a class of multi-channel cosine-modulated filter banks
satisfying the perfect reconstruction (PR) property using an IIR prototype
filter. By imposing a suitable structure on the polyphase filter coefficients,
we show that it is possible to greatly simplify the PR condition, while
preserving the causality and stability of the system. We derive closed-form
expressions for the synthesis filters and also study the numerical stability of
the filter bank using frame theoretic bounds. Further, we show that it is
possible to implement this filter bank with much lower number of arithmetic
operations when compared to FIR filter banks with comparable performance. The
filter bank's modular structure also lends itself to efficient VLSI
implementation.
