Laterally Excited Bulk Acoustic Resonators with Convex Interdigital Electrodes towards SHF Applications

Suppressing spurious modes is currently a key issue in the design of laterally excited bulk acoustic resonators (XBARs). In this paper, we fabricated and characterized an XBAR with convex electrodes towards SHF applications, named C-XBAR. The mechanism of acoustic wave propagation and the suppression of spurious modes in C-XBAR is investigated using finite element analysis (FEA). The C-XBAR is fabricated using a 358 nm Z-cut LNOI wafer. The measured C-XBAR exhibits a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Kₜ²</tex> of 19.42% at 5.322 GHz with a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Qₘₐₓ</tex> of 343, where the theoretical analysis was validated. Furthermore, the power-handling capability of C-XBAR is measured +25.19 dBm. The C-XBAR shows great potential in the applications of high-performance filters for 5G/6G communication.