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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 (LiNbO ₃ /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 k ₓ^2 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 LiNbO ₃ /SiC substrate for commercial applications in 5G new radio (NR) and Wi-Fi 5/6 bands.
Zheng et al. (2023) studied this question.