Physics

Geology

Surface acoustic wave

Mathematics

Resonator

Analytical Chemistry (journal)

Optics

Oceanography

Coupling (piping)

Orientation (vector space)

Composite material

Chemistry

Materials science

Geometry

Substrate (aquarium)

Layer (electronics)

Coupling coefficient of resonators

Chromatography

Optoelectronics

IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control

In response to the increased mobile data traffic, there is a growing need for more low-loss RF band filters with steep frequency characteristics, and high-quality ( Q )-factor and low-temperature coefficient of frequency (TCF) resonators are required to achieve this. We previously reported that for a surface acoustic wave (SAW) resonator on a three-layer structure, which is composed of a thin LiTaO3 (LT) plate whose orientation is 50° rotated YX propagation, SiO2 layer, and AlN layer on a Si substrate, a Q-factor several times higher than that of an SAW resonator on a standard 42° rotated YX propagation LiTaO3 (42YX-LT) substrate could be obtained. In this study, we investigated this layer structure and found that a two-layer structure, in which the AlN layer is removed, achieves a high Q -factor. Numerical analyses using a finite element method showed that the acoustic wave energy can be confined to the surface of the two-layer substrate, and the TCF and electromechanical coupling coefficient ( k2 ) were improved by optimizing the thickness of each layer. We fabricated and evaluated prototype one-port resonators with the two-layer structure and the standard 42YX-LT SAW substrate with resonant frequencies from 0.95 to 3.6 GHz. An improvement of the Q-factor of 3 to 4 times compared with that of the resonator with standard 42YX-LT substrate was observed for the two-layer structure, which means that a reduction of complexity of the layer structure could be obtained without performance loss. The two-layer structure was applied to a 2.4-GHz band Wi-Fi filter to achieve high performances such as low-loss, better steepness, and high attenuation.

High-Performance SAW Resonator With Simplified LiTaO<sub>3</sub>/SiO<sub>2</sub> Double Layer Structure on Si Substrate

High-Performance SAW Resonator With Simplified LiTaO3/SiO2 Double Layer Structure on Si Substrate

High-Performance SAW Resonator With Simplified LiTaO₃/SiO₂ Double Layer Structure on Si Substrate