Optimal design of stable IIR digital filters using unconstrained optimization

摘要

This paper considers the unconstrained optimal design of stable IIR digital filters by the Nelder-Mead simplex direct search. The filter design problem is formulated so that the denominator polynomial of the transfer function is expressed as a product of second-order sections with complex conjugate poles. By considering the above factorized denominator polynomial with restricted variable ranges, the proposed formulation provides a design technique that always guarantees the stability of the resultant IIR digital filter. Finally, numerical examples are given to show that the proposed technique can design optimal or sub optimal stable IIR digital filters, compared with existing techniques.