High-Performance Surface Acoustic Wave Devices Using LiNbO3/SiO2/SiC Multilayered Substrates

• Published in: IEEE transactions on microwave theory and techniques Vol. 69; no. 8; pp. 3693 - 3705
• Main Authors: Shen, Junyao, Fu, Sulei, Su, Rongxuan, Xu, Huiping, Lu, Zengtian, Xu, Zhibin, Luo, Jingting, Zeng, Fei, Song, Cheng, Wang, Weibiao, Pan, Feng
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 5G mobile communication; Bandwidth; Coupling coefficients; Electrical impedance; Electromagnetic wave filters; Finite element method; Frequency filters; Insertion loss; Large bandwidth; LiNbO; Lithium niobates; multilayered substrate; Performance evaluation; power durability; Resonators; SiC; Silicon carbide; Silicon dioxide; Single crystals; Substrates; surface acoustic wave (SAW); Surface acoustic wave devices; Surface acoustic waves; temperature stability
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2021.3077261

The rapid development of the fifth-generation (5G) wireless system is driving strong demand for high-performance radio frequency filters. This work studies shear horizontal surface acoustic wave (SAW) devices using 15°-rotated <inline-formula> <tex-math notation="LaTeX">Y </tex-math></inline-formula>-cut <inline-formula> <tex-math notation="LaTeX">X </tex-math></inline-formula>-propagating (15°Y-X) LiNbO 3 /SiO 2 /SiC multilayered substrates. Single-crystalline 15°Y-X LiNbO 3 films are bonded to SiO 2 /SiC handling substrates by the smart cut technology. On the basis of accurate finite-element-method simulations, LiNbO 3 /SiO 2 /SiC wafer configurations are optimized to suppress spurious resonance due to Rayleigh-mode and transverse-mode responses, and one-port resonators with a clean spectrum, a high electromechanical coupling coefficient of 22.00%, and an admittance ratio (impedance ratio) over 65 dB are successfully implemented. Based on the characteristics of the resonators, high-performance filters with a center frequency of 1.28 GHz, a large 3-dB fractional bandwidth of 16.65%, and a low minimum insertion loss of 1.02 dB are successfully designed and fabricated. Furthermore, no ripples in the passband of the filters are observed. Additionally, the filters exhibit a temperature coefficient of center frequency of −63.8 ppm/°C and a large power durability of 33.2 dBm. This work confirms the high performances of the SAW devices using the 15°Y-X LiNbO 3 /SiO 2 /SiC multilayered substrate, and this type of SAW device exhibits a prospect of commercial applications in the 5G wireless system.