Automatic extraction and design of SAW resonator COM parameters via PSO-P matrix joint optimization

Surface acoustic wave (SAW) devices are key components in radio-frequency communication and sensing systems, whose performance optimization relies heavily on accurate simulation models. As a widely adopted theoretical tool, the coupling of modes (COM) model typically requires multiple types of COMSOL multiphysics simulations and complex post-processing steps for parameter extraction, resulting in cumbersome and inefficient workflows. To address this issue, this paper proposes an automated COM parameter extraction method based on the integration of particle swarm optimization (PSO) algorithm and P-matrix. The proposed method obtains the admittance response of the resonator through only a single COMSOL frequency domain simulation and employs the weighted mean square error (WMSE) as the objective function for global fitting via PSO, thereby enabling efficient and automatic extraction of COM parameters and significantly simplifying the traditional multi-step procedure. Based on the extracted parameters, systematic mappings illustrating the variations of COM parameters with electrode thickness and metallization ratio were established. Furthermore, the influence of key structural parameters, such as the number of interdigital transducer (IDT) finger pairs and reflector electrodes, on resonator performance metrics including return loss (S₁₁) and quality factor (Q-value) was analyzed. Experimental results from SAW resonators with various structural parameters fabricated on 128° Y-X LiNbO₃ substrates show excellent agreement between the measured responses and COM-based simulations, with performance trends consistent with model predictions, validating the feasibility and reliability of the proposed PSO-P-matrix joint optimization method.