Quadratic Programming Approach to Coupled Resonator Filter CAD

A computer-aided design technique for coupled resonator filters is presented. The technique is formulated as a bound constrained quadratic programming (QP) problem and predicated upon coupling matrix identification. The identification relies on the derivation of a rational model of the filter response and is formulated as a bound constrained QP problem. The definition of the optimization procedure in the form of a QP problem with an assumption of linear dependence of the coupling coefficients on filter geometrical dimensions leads to a significant reduction of the number of the full-wave electromagnetic simulations required to satisfy specifications. The proposed procedure is verified by designing and fabricating three microstrip filters