Improved-efficacy optimization of compact microwave passives by means of frequency-related regularization
Date
2020Item Type
ArticleAbstract
Electromagnetic (EM)-driven optimization is an important part of microwave design, especially
for miniaturized components where the cross-coupling effects in tightly arranged layouts make traditional
(e.g., equivalent network) representations grossly inaccurate. Efficient parameter tuning requires reasonably
good initial designs, which are difficult to be rendered for newly developed structures or when re-design
for different operating conditions or material parameters is required. If global search is needed, due to
either the aforementioned issues or multi-modality of the objective function, the computational cost of the
EM-driven design increases tremendously. This paper introduces a frequency-related regularization as a way
of improving the efficacy of simulation-based design processes. Regularization is realized by enhancing the
conventional (e.g., minimax) objective function using a dedicated penalty term that fosters the alignment of
the circuit characteristics (e.g., the operating frequency or bandwidth) with the target values specified by
the design requirement. This leads to smoothening of the objective function landscape, improves reliability
of the optimization process, and reduces its computational cost as compared to the standard formulation.
An added benefit is the increased immunity to poor initial designs and multi-modality issues. In particular,
regularization can make local search routines sufficient in situations where global optimization would
normally be necessary. The presented approach is validated using two miniaturized circuits, a rat-race and
a branch line coupler. The numerical results demonstrate its superiority over conventional design problem
formulations in terms of reliability of the optimization process.
Author
Koziel, Slawomir
Pietrenko-Dabrowska, Anna
Al-Hasan, Muath