IIR digital filter design by partial second-order factorization and iterative WLS approach
Aimin Jiang, Hon Keung Kwan, Yanping Zhu, Ning Xu, Xiaofeng Liu · 2016
In this paper, a novel algorithm is developed for the minimax design of IIR digital filters. Using a partial second-order factorization (PSOF), the denominator polynomial of an IIR digital filter is decomposed as a cascade of second-order factors (SOFs) and a single higher-order factor (HOF). This is inspired by the fact that, when some poles are closer to the boundary of the stability domain, the other poles tend to stay inside the stability domain such that the specified frequency response can be best approximated. By means of the PSOF, stability constraints are only imposed on a limited number of SOFs and, thus, a better design could be attained. The proposed algorithm successively updates SOFs and HOF. To further reduce its computational complexity, the iterative weighted least-squares approach is applied to optimize each SOF or HOF. Simulation results demonstrate that the proposed algorithm can attain the balance between computational efficiency and design accuracy.