A new structure for adaptive IIR filters with guaranteed stability

In this paper, a new condition, with which the bounded-input bounded-output (BIBO) stability of the adaptive filters can be ensured, is derived. Based on this result, a new structure for adaptive IIR filters is proposed. The basic feature of this structure is to cascade the denominator of the IIR filter transfer function with a set of 2nd-order sub-filters that are implemented with a normal state-space realization. Simulations are given to support the theoretical results and to compare the performance of the proposed structure with that of the classical direct-form II structure.