A 1.65 GHz Lithium Niobate A1 Resonator with Electromechanical Coupling of 14% and Q of 3112

Abstract

This paper reports on the demonstration of a 1.65 GHz A1 mode lithium niobate resonator with a high electromechanical coupling ( ${k_{t}}^{2}$ ) of 14%, a high-quality factor ( $Q$ ) of 3112, and a near spurious-free response. The 1.65 GHz resonance has been achieved by exploiting the high phase velocity of the first-order antisymmetric (A1) Lamb wave mode in a Y-cut lithium niobate (LiNbO 3 ) thin film, while spurious mode suppression is accomplished with electrode optimization. The performance demonstrated herein marks the first time that a new resonator technology outperforms surface acoustic wave (SAW) resonators and thin-film bulk acoustic resonators (FBARs) regarding the figure of merit (FoM) in the 1–6 GHz frequency range. Thus, the A1 mode lithium niobate resonator in this work promises a new platform for the fifth-generation (5G) front-end filtering.