Recursive least squares-like algorithms for the adaptive second-order lattice notch filter

Two new adaptive second-order infinite impulse response (IIR) notch filters with fast convergence rate, accurate estimation of notch frequency, and modest realization complexity are proposed in this paper. It is proven that the optimum filter coefficient can be determined by using the minimum output energy (MOE) criterion. Based on it, a simplified equivalent adaptive system is derived, and two recursive least squares (RLS)-like algorithms are presented to adaptively estimate the filter coefficient. Extensive simulations show the effectiveness and robustness of the new adaptive IIR notch filters.