Reduced-Cost Gradient-Based Optimization of Compact Microwave Components through Adaptive Broyden Updates

In this paper, electromagnetic (EM)-driven design optimization of miniaturized microwave components using expedited trust-region gradient search is presented. Our approach involves a combination of finite differences and a rank-one Broyden formula to update the circuit response Jacobian. The latter is performed for selected parameters depending on the alignment between the most recent design relocation and the coordinate system axes. The alignment threshold is adaptively adjusted based on the algorithm convergence status. Comprehensive numerical validation of the proposed algorithm involving a compact microstrip coupler as well as a three-section CMRC-based impedance transformer is provided demonstrating significant speedup of up to 48 percent as compared to the benchmark algorithm.