Wideband and Low-Loss Surface Acoustic Wave Filter Based on 15° YX-LiNbO₃/SiO₂/Si Structure

Material Foundation for Future 5G Technology

“…For 5G, increasing the filter bandwidth requires enhanced piezoelectric coupling. Scandium-doped aluminum nitride (ScAlN) can solve this problem, but the manufacturing becomes more challenging, motivating the transition to lithium niobate (LiNbO 3 ) materials. , The precise deposition of the piezoelectric material, electrode configuration, acoustic reflector, and parasitic effects are key factors for enhanced coupling. Innovative structures such as XBAR and other options, including dielectric waveguides, on-chip filtering structures, cavity waveguides, and microstrips, can lead to filters operating at even higher frequencies.…”

Fractional Bandwidth up to 24% and Spurious Free SAW Filters on Bulk 15°YX-LiNbO3 Substrates Using Thickness-Modulated IDT Structures

“…Moreover, it should also be pointed out that YX-LiNbO 3 are commercial substrates that are commonly used in the current SAW industry, and the device was fabricated using a standard optical lithography process. Compared to previous work based on LN/SiO 2 /Si platforms [ 17 ], the FBW and passband flatness are simultaneously improved, while the preparation costs are greatly reduced. Hence, the low-cost mass production of spurious-free ultra-wideband SAW filters appears to be quite feasible when using our proposed approach.…”

“…It was confirmed that the filters were measured with the spurious-free response. Compared to previous work based on LiNbO 3 film-bonded substrates [ 17 , 18 ], the device performance, which includes the frequency, FBW, and passband flatness, in this work are simultaneously improved. Moreover, the complexity of the manufacturing processes and the preparation costs are greatly reduced.…”

“…Several approaches have been proposed and carried out to overcome this limitation and to improve the BW of filters, such as by adopting passive electromagnetic component-aided technologies, utilizing piezoelectric films on insulator layered structures, or using plate acoustic wave modes [ 12 , 13 , 14 , 15 , 16 ]. For example, we recently reported on wideband SAW filters with a large 3-dB FBW of over 20% on LiNbO 3 that had been film-bonded on a handling substrate [ 17 , 18 ]. However, the fabrication processes of LiNbO 3 film-bonded substrates are complex and require the precise control of each film’s thickness.…”

Influence of the Core Pillar Height on the Bandgap Characteristics of Piezoelectric Phononic Crystals with Ring-Shaped Grooves

“…Using light and acoustic waves [1] is the most practical way to reach this aim. Surface acoustic waves (SAWs) have been receiving extensive attention on various research and application areas related to delay lines [2], filters [3,4], microfluidics [5][6][7], gas-detection [8,9], mass detection [10] and biodetection applications [11,12]. Due to these wide ranges of research and application areas, SAW devices have drawn significant interest in recent decades.…”