Stair-Step BAW Resonator Frames for Spurious Mode Suppression

The resonator structure is segmented into multiple functional layers including piezoelectric layers, conductive layers, dielectric layers, and acoustic reflectors arranged in a stacked configuration. This segmentation allows each layer to perform specific functions for energy confinement and resonance control, reducing energy leakage while maintaining manageable structural complexity

The resonator employs a nested structure where inner components are surrounded by outer components with specific acoustic impedance characteristics. The piezoelectric layers are nested between conductive layers, which are in turn nested within dielectric layers and acoustic reflectors, creating concentric zones of energy confinement that reduce spurious modes and improve quality factor

The resonator structure implements local quality variations through different material layers positioned at specific locations. Acoustic reflectors with high acoustic impedance are placed at the edges and interfaces to locally confine energy, while the central region maintains the thickness mode resonance characteristics. This local differentiation suppresses edge effects and spurious modes while preserving high-frequency operation

Dielectric layers and acoustic reflectors serve as intermediary structures between the piezoelectric layers and the surrounding environment. These intermediary layers mediate the acoustic energy transmission, preventing direct energy leakage at edges and interfaces, thereby stabilizing the resonant frequency while enabling high-frequency operation