3.75 GHz AlN Lamb wave resonator with hole-like acoustic reflection structure

Quality factor improvement in Lamb wave resonators (LWRs) have always been the research hotspot. In this work, a 3.75 GHz A1 mode AlN-based LWR with hole-like acoustic reflection structure is proposed. This structure forms an acoustic impedance mismatch boundary to limit the transverse acoustic wave to the resonant region to avoid acoustic wave leakage. The measured Q factor at the parrel resonant frequency (about 3.8 GHz) increases from 747 of the conventional resonator to 1137 using hole-like structure. The proposed structure improves the Q factor without additional process and shows great potential in high-performance Lamb wave resonators and filters.