Iterative reweighted minimax phase error design of IIR digital filters based on a modified constraint model

Iterative reweighted minimax phase-error designs of infinite impulse response (IIR) digital filters with preset magnitude-error are nonconvex problems due to the nonconvexity of the lower-bound constraint of magnitude-error at any passband frequency point. In order to get a better performance of the digital filters, we use a modified constraint model to approximate the nonconvex constraint model. With the modified constraint model, the iterative reweighted minimax phase-error design has obtained better filters. Design examples demonstrating the effectiveness of the modified constraint model based iterative reweighted minimax phase-error design method are provided.