Near 5-GHz Longitudinal Leaky Surface Acoustic Wave Devices on LiNbO3/SiC Substrates

• Published in: IEEE transactions on microwave theory and techniques Vol. 72; no. 3; pp. 1480 - 1488
• Main Authors: Zheng, Pengcheng, Zhang, Shibin, Wu, Jinbo, Zhang, Liping, Yao, Hulin, Fang, Xiaoli, Chen, Yang, Huang, Kai, Ou, Xin
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2024; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 5G mobile communication; Acoustics; Design improvements; Electromagnetic wave filters; Fifth-generation (5G) N79 band; Filter design (mathematics); filters; Insertion loss; lithium niobate on silicon carbide (LiNbO₃/SiC); Lithium niobates; longitudinal leaky surface acoustic wave (LL-SAW); Microwave filters; Resonant frequencies; Resonant frequency; Resonator filters; Resonators; Silicon carbide; Silicon substrates; spurious mode suppression; Substrates; Surface acoustic wave devices; Surface acoustic waves; Thin films
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/TMTT.2023.3305078

This work demonstrates a group of longitudinal leaky surface acoustic wave (LL-SAW) resonators and filters using thin-film X-cut lithium niobate on silicon carbide (LiNbO3/SiC). An improved design that exploits a nonstandard reflector (NSR) structure to suppress the lateral overtone spurious mode in the LL-SAW response is demonstrated. The fabricated resonators show scalable resonant frequencies from 3.75 to 4.95 GHz, admittance ratios (ARs) between 56.0 and 64.1 dB, and large <inline-formula> <tex-math notation="LaTeX">{k} _{t}^{{2}} </tex-math></inline-formula> between 18.3% and 20%. The fabricated filter with a center frequency of 4.84 GHz shows a minimum insertion loss (IL) of 0.88 dB, an out-of-band rejection of 26 dB, and a 3-dB bandwidth (BW) of 457 MHz, partially covering the fifth-generation (5G) N79 band. The filter design tradeoff between SH mode suppression and BW is also demonstrated. The results herein show the great potential of LL-SAW technologies using LiNbO3/SiC substrate for commercial applications in 5G new radio (NR) and Wi-Fi 5/6 bands.