Optimization Synthesis Technique for Cross-Coupled Filter with Frequency Dependent Couplings

Cross-coupled filters with small volume and the high performance are applied widely in various microwave systems. However, the number of finite transmission zeros for cross-coupled filters is limited. However, a cross-coupled filter with frequency dependent couplings can realize more finite transmission zeros than the traditional cross-coupled filters when the filter order is the same. A novel fast filter synthesis technique with frequency dependent couplings is presented in this paper. The global optimization algorithm Genetic Algorithm (GA) searches the optimal solution. If the solution meets the requirement, stop the optimization. Otherwise, the solution of GA as the initial value for Solvopt optimization to search the optimal solution. Three numerical examples show the validity of the synthesis technique in this paper.