Nguyen Kristi, Chulukhadze Vakhtang, Stolt Eric, Braun Weston, Segovia-Fernandez Jeronimo, Chakraborty Sombuddha, Rivas Juan, Lu Ruochen
IEEE Trans Ultrason Ferroelectr Freq Control. 2023 Nov;70(11):1536-1543. doi: 10.1109/TUFFC.2023.3303123. Epub 2023 Nov 1.
Piezoelectric power converters, where acoustic resonators replace the inductors as energy storage elements, promise much higher power density and higher efficiency compared to conventional circuits. Recently, lithium niobate (LiNbO3) piezoelectric resonators have been integrated within power converter circuits, showing good conversion efficiency, thanks to their high quality factor ( Q ) and electromechanical coupling ( k ). However, the converter output power range is limited by large spurious modes near resonance. This work reports a near-spurious-free LiNbO3 thickness shear (TS) resonator, demonstrating a high Q of 3500 and k of 45% at 5.94 MHz, with a fractional suppressed region of 35%. First, we identify the best LiNbO3 crystal orientation for efficient TS resonators. Then, we propose a novel acoustic design without busbars for spurious suppression, which is extensively simulated, fabricated, and characterized. Further analysis is done to identify existing spurious modes in our proposed design, specifically the effect of dicing on our TS resonator design. Upon optimization, LiNbO3 TS resonators could potentially empower a new design space for low-loss and compact power converters.
压电功率转换器中，声学谐振器取代电感作为能量存储元件，与传统电路相比有望实现更高的功率密度和更高的效率。最近，铌酸锂（LiNbO₃）压电谐振器已集成到功率转换器电路中，由于其高品质因数（Q）和机电耦合（k），显示出良好的转换效率。然而，转换器的输出功率范围受到共振附近大杂散模式的限制。这项工作报道了一种几乎无杂散的LiNbO₃厚度剪切（TS）谐振器，在5.94 MHz时展示了3500的高Q值和45%的k值，抑制分数区域为35%。首先，我们确定了用于高效TS谐振器的最佳LiNbO₃晶体取向。然后，我们提出了一种无母线的新型声学设计用于杂散抑制，并进行了广泛的模拟、制造和表征。进一步分析以确定我们提出的设计中现有的杂散模式，特别是切割对我们TS谐振器设计的影响。经过优化，LiNbO₃ TS谐振器可能为低损耗和紧凑型功率转换器开辟一个新的设计空间。
