Bulk Acoustic Wave Resonator With Suppressed Energy Loss Using Improved Lateral Structure

A bulk acoustic wave (BAW) resonator with suppressed energy loss is proposed. Implemented with air edge reflector and current spreading electrode along the perimeter region of the BAW, the resonator successfully suppresses the acoustic wave leakage and the electric energy loss as well. As results of optimized lateral structure, the Q-factor at anti-resonance frequency (Q(a)) is significantly improved to over 2100. Furthermore, the peak insertion loss exhibits as low as 0.04 dB and effective electro-mechanical coupling coefficient (kt(2)), which is essential to achieve wide band-width of RF filters, is 6.54%.