Topological effect design for enhancing solidly mounted resonators performance

Bulk acoustic wave (BAW) filters are essential in 5G wireless communication yet suffer from limited spectral selectivity near band edges. Here, we propose a topologically engineered acoustic reflector integrated into a solidly mounted resonator (SMR) to enhance wave confinement and coupling efficiency. By tuning the Zak phase through the SiO2 layer thickness in the topological reflector, we induce robust interface states that suppress reflections and improve acoustic energy transmission. Simulation results show that integrating this topological SMR into a hybrid integrated passive devices–BAW filter achieves a high-loss notch at 3851 MHz with −22.77 dB suppression, outperforming conventional LC filters. We also demonstrate that the electromechanical coupling coefficient is locally enhanced near topological resonance conditions, enabling frequency-selective control through geometric tuning. This work establishes a practical framework for topological acoustic reflectors in high-performance RF filter design, offering a scalable and CMOS-compatible approach for next-generation wireless systems.