6.5GHz Longitudinal Leaky SAW Filter Using LiNbO₃-on-SiC Structure for Wi-Fi 7

This work focused on solving the filtering scheme for challenging Wi-Fi 7 bands and successfully implemented the surface acoustic wave (SAW) filters exploiting longitudinal leaky (LL) modes based on thin film X-cut LiNbO₃-on-SiC (LNOSiC). Here, we initially investigated the relationship between the normalized LiNbO₃ thickness (hLN/λ) and the resonator response theoretically and experimentally. The lithium niobate film with a thickness of 270 nm was chosen to balance loss and high-frequency side spurious modes. LL-SAW resonators with wavelengths (λ) ranging from 0.92 to 1.08 µm were fabricated, showing scalable resonant frequencies from 5.8 to 6.6 GHz and large K² of about 19%. An LL-SAW filter with a passband range of 6.297–6.824 GHz, a large 3-dB bandwidth of 527 MHz, and a low insertion loss (IL) of 1.29 dB was successfully realized. The filter meets the requirements of frequency (6 GHz) and channel bandwidth (320 MHz) of Wi-Fi 7, potentially providing a front-end filtering solution for Wi-Fi 7 commercial applications.