Alcorta Galvan R, Croenne C, Dubus B, Loiseaux B, Eustache E, Bertrand M, Hladky-Hennion A-C
IEEE Trans Ultrason Ferroelectr Freq Control. 2024 Oct;71(10):1302-1313. doi: 10.1109/TUFFC.2024.3441531. Epub 2024 Oct 10.
This work presents the development of switchable surface acoustic wave (SAW) resonators fabricated on a LiNbO3 substrate, which uses the electrical Bragg bandgap concept to control the resonance frequency. The modification of the electrical condition of electrode arrays shifts their bandgap center frequency, which in turn changes the effective cavity length and resonance frequency of the resonator. This method uses the electrodes already present in SAW devices, thus reducing the complexity of potentially tunable SAW components. In this article, the electrodes that make up the cavity mirrors are connected into interdigitated comb pairs (IDCPs), reducing the necessary number of switches for operation. Finite-element method (FEM) simulations are used to analyze resonator operation and design difficulties are discussed. Frozen (with no possibility of switching) and switchable versions of a chosen resonator structure are fabricated to experimentally showcase resonator operation. It is found that it is possible to design switchable SAW resonators, which require a single switch and present a relative frequency jump of around 2.3%. Finally, frozen single-cell and four-cell ladder filters are fabricated as a proof of concept of a switchable SAW filter.
这项工作展示了在铌酸锂衬底上制造的可切换表面声波（SAW）谐振器的发展情况，该谐振器利用电布拉格带隙概念来控制谐振频率。电极阵列电条件的改变会使其带隙中心频率发生偏移，进而改变谐振器的有效腔长和谐振频率。此方法利用了SAW器件中已有的电极，从而降低了潜在可调谐SAW组件的复杂性。在本文中，构成腔镜的电极被连接成叉指梳状对（IDCPs），减少了操作所需的开关数量。采用有限元方法（FEM）模拟来分析谐振器的工作情况，并讨论了设计难点。制造了选定谐振器结构的冻结（不可切换）版本和可切换版本，以通过实验展示谐振器的工作情况。研究发现，可以设计出需要单个开关且相对频率跳变约为2.3%的可切换SAW谐振器。最后，制造了冻结的单单元和四单元梯形滤波器，作为可切换SAW滤波器概念验证。
