On decision-making strategies for improved-reliability size reduction of microwave passives: Intermittent correction of equality constraints and adaptive handling of inequality constraints

Slawomir Koziel, Anna Pietrenko-Dabrowska*, Marzieh Mahrokh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Design optimization of passive microwave components is an intricate process, especially if the primary objective is a reduction of the physical size of the structure. The latter has become an important design consideration for a growing number of modern applications (mobile communications, wearable/implantable devices, internet of things), where miniaturization is imperative due to a limited space allocated for the electronic circuitry. Optimization-based size reduction is a heavily constrained task, with several acceptance thresholds imposed on electrical characteristics of the system. The challenges are pronounced whenever equality constraints are involved (e.g., related to power split ratio requirements), in which case the feasible space is a thin set, thereby difficult to be explored throughout the optimization process. This feature makes conventional methods, such as penalty function approaches or algorithms with explicit constraint handling, of limited reliability. In this paper, we introduce a novel technique for reliable control of equality constraints in simulation-driven size reduction of microwave components. Our methodology involves an intermittent optimization-based correction of equality constraints. This is essentially a knowledge-based decision-making strategy implemented as a supplementary optimization stage, and launched before each iteration of the core algorithm. Constraint violation is reduced without being detrimental to the remaining figures of merit, in particular, the circuit size and inequality constraints. Meanwhile, inequality constraints are handled using a penalty function approach with adaptive adjustment of penalty coefficients. The proposed technique facilitates exploration of the feasible space, and allows for achieving reduced miniaturization rates in comparison to the benchmark methods, while ensuring a reliable control of the design constraints. These advantages have been demonstrated using four microstrip couplers, with consistent results obtained for all considered circuits.

Original languageEnglish
Article number109745
JournalKnowledge-Based Systems
Volume255
DOIs
Publication statusPublished - 14 Nov 2022

Bibliographical note

Funding Information:
The authors would like to thank Dassault Systemes, France, for making CST Microwave Studio available. This work is partially supported by the Icelandic Centre for Research (RANNIS) Grant 217771 and by National Science Centre of Poland Grant 2020/37/B/ST7/01448 .

Publisher Copyright:
© 2022 Elsevier B.V.

Other keywords

  • Constrained optimization
  • Constraint correction
  • Decision-making strategies
  • EM-driven design
  • Equality constraints
  • Microwave design
  • Miniaturization

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