Performance Evaluations of Bio-Inspired Adaptive Algorithms Applied to IIR Digital Filters Designed with Coupled Form Second Order Sections

During many past decades it has been known that when using finite word-length binary arithmetic in IIR digital filters, coupled form second order sections implement conjugate-pair poles that have relatively uniform pole locations located inside the unit circle in the z-plane. However, coupled form 2nd order sections could never be used in IIR adaptive filter designs using steepest descent adaptive algorithms due to the multi-modal error surfaces created by coupled form structures. Results presented in this paper demonstrate that the LFFA can be effectively applied to IIR adaptive filter structures designed with parallel or cascade second order coupled form sections.