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

• Published in: IEEE MTT-S International Microwave Symposium digest pp. 804 - 807
• Main Authors: Sun, Mijing, Zhang, Shibin, Zheng, Pengcheng, Fang, Xiaoli, Ou, Xin
• Format: Conference Proceeding
• Language: English
• Published: IEEE 16.06.2024
• Subjects: Bandwidth; Filtering; lithium niobate; longitudinal leaky mode; Resonant frequency; Resonator filters; SAW filters; Silicon carbide; surface acoustic wave (SAW) filter; Surface acoustic waves; Wi-Fi 7 bands
• ISSN: 2576-7216
• DOI: 10.1109/IMS40175.2024.10600262

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 LiNb03-on-SiC (LNOSiC). Here, we initially investigated the relationship between the normalized LiNb03 thickness (\mathbf{h}_{\text{LN}}/\lambda) 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-SA W resonators with wavelengths (\lambda) ranging from 0.92 to 1.08 \mu\mathrm{m} were fabricated, showing scalable resonant frequencies from 5.8 to 6.6 GHz and large K2 of about 19%. An LL-SA W 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.