New nonlinear adaptive IIR digital filters

A new structure and its adaptive algorithm of a nonlinear adaptive IIR digital filter is presented. With the use of a nonlinear saturation function at the output, the stability problem adherent to conventional linear adaptive IIR digital filters can be avoided. The individual parameter adaptation scheme is developed into the adaptive algorithm to optimally adjust each parameter at every iteration. Based on the application in adaptive system identifications of linear IIR digital filters, simulation results obtained show that the new nonlinear adaptive IIR digital filters outperform those of linear adaptive IIR digital filters in terms of convergence speed and final output error residuals