2 to 16 GHz Fundamental Symmetric Mode Acoustic Resonators in Piezoelectric Thin-Film Lithium Niobate

TL;DR

This paper demonstrates the design and fabrication of thin-film lithium niobate acoustic resonators operating in the fundamental symmetric Lamb mode at frequencies up to 16 GHz, suitable for 6G signal processing applications.

Contribution

It introduces scaled S0 mode resonators in lithium niobate reaching 16 GHz, with performance metrics surpassing current state-of-the-art devices.

Findings

Achieved a 14.9 GHz resonator with Q of 391

Demonstrated a k2 of 6% at high frequency

Surpassed existing resonator performance in the 6-16 GHz range

Abstract

As 5G connectivity proliferates, signal processing applications at 6G centimeter bands have gained attention for urban wireless capacity expansion. At sub-5 GHz, acoustic resonators operating in the fundamental symmetric (S0) Lamb mode hold significant promise if frequency scaled to the 6G centimeter bands. Concurrently, the lateral wavelength dependency and the traveling wave nature of S0 mode enable monolithic multi-frequency fabrication, transversal filters, correlators, and other compact signal processing components. In this work, we present thin-film lithium niobate (LN) S0 resonators scaled up to 16 GHz. Specifically, we study the characteristics of the S0 mode as the wavelength is minimized and showcase a device at 14.9 GHz with a Bode Q maximum of 391, a k2 of 6%, and a figure of merit (FoM) of 23.33, surpassing the state-of-the-art (SoA) in its frequency range.