Near-Zero TCF and Spurious-Free Wideband SAW Device on LNOI platform

Lithium niobate on insulator (LNOI) platform has emerged as a promising solution for fabricating wideband and low-loss surface acoustic wave (SAW) filters in 5G communication. However, SAW devices on LNOI platform face a new set of challenges, such as large temperature coefficient of frequency (TCF) and spurious modes, which impairing their recognition by the industry. In this work, the responses of SAW resonators with different dimensions and stack thickness on 32°Y-X LN/SiO
2
/Si multilayered substrates were evaluated by finite element method. By careful design and optimization, spurious modes like Rayleigh waves and higher order modes were eliminated and near-zero TCF SAW resonators were achieved. Resonators with different dimensions were fabricated and measured, which demonstrates superb performance with a high K
²
of 22.8%, a high Q value of 1050, a large admittance ratio (AR) of ~ 80 dB and an ultralow TCF of ~ -2 ppm/°C. This work demonstrates high performance SAW resonator on the LNOI platform, and it also support the future adoption of LNOI platform for high-performance filtering solution for 5G applications.