Near-Zero Drift and High Electromechanical Coupling Acoustic Resonators at > 3.5 GHz

Abstract

In this article, near-zero drift and high electromechanical coupling acoustic resonators have been designed and demonstrated. The acoustic resonator is based on Lamb acoustic waves in a bimorph composed of lithium niobate on silicon dioxide. Our approach breaks through a performance boundary in conventional Lamb-wave resonators by introducing the bimorph while operating at higher order resonant modes. This enables the resonator to achieve frequency scalability, a low-temperature coefficient of frequency, and high electromechanical coupling altogether. The electromechanical coupling and temperature coefficient of the resonator were analytically optimized for the A 3 mode through adjusting the thicknesses of different materials in the bimorph. Resonators with different dimensions and stack thickness were fabricated and measured, resulting in a temperature coefficient of frequency ranging from −17.6 to −1.1 ppm/ • C, high electromechanical coupling ranging from 13.4% to 18%, and quality factors up to 800 at 3.5 GHz. The achieved specifications are adequate for fifth-generation (5G) sub-6-GHz frequency bands n77 and n78. Index Terms-Acoustic resonators, fifth generation (5G), lithium niobate on insulator (LNOI), low-temperature coefficient of frequency (TCF), microelectromechanical systems (MEMS), new radio (NR), piezoelectricity. I. INTRODUCTION T HE fifth-generation mobile network (5G) is a global wireless standard advancing the prevalent connectivity between people, machines, and devices [1], [2]. The third-generation partnership project (3GPP), a collective project partnership of mobile system manufacturers, has played a critical role in the development and deployment of the 5G standard [1]. Specifically, 5G new radio (NR) uses modulation schemes, waveforms, and access technologies, enabling increased data rates, coverage, reliability, capacity, and low latency [2]. 5G is driven by consumers and industrial trends, such as enhanced mobile broadband (eMBB), Internet of Things (IoT), smart vehicles, and healthcare/critical Manuscript

Design and Analysis of Lithium–Niobate-Based Laterally Excited Bulk Acoustic Wave Resonator with Pentagon Spiral Electrodes

“…As p increases from 5 µm to 20 µm, the measured decreases from 21.3% to 15.8% gradually as shown in Figure 8 b. To better understand the variation of the with different p , we adopt Berlincour’s Formulations (7) and (8) for electromechanical coupling calculation, which can be expressed as [ 27 , 28 , 29 ] where K 2 is the electromechanical coupling, U m , U d , and U e are the mutual energy, electrical energy, and elastic energy. E , d , T and V are the electric field, the piezoelectric coefficient, stress, and volume of the piezoelectric material, respectively.…”

Serially connected strip-type acoustic wave resonator using X-40°Y LiNbO3 (XSAR)—feasibility study using macro model

“…Additionally, the magnitudes of the stress and E field are perfectly overlapped in a cosine shape, indicating a stronger coupling compared with other modes such as A 1 mode, whose E field is evenly distributed along thickness direction. 27) The calculated piezoelectric constants of LN as a function of the Euler angle θ and ψ are shown in Figs. 3(a) and 3(b), respectively.…”