Ultrawide-Band SAW Devices Using SH0 Mode Wave with Increased Velocity for 5G Front-Ends

In this work, the phase velocity (V
p
) and the electromechanical coupling factors (k
t
²
) of SH0 modes excited in X-cut LiNbO
3
(LN) films were studied by finite element analysis, and both of them show strong dispersion when LN films are bonded to foreign substrates. In particular, the V
p
of the SH0 mode in LiNbO
3
-on-SiC (LNOSiC) substrate can exceed 1.5 times the value in LN plate, so as the operating frequency. 4-inch LNOSiC substrate was fabricated by ion-cutting process. A group of SH0 mode resonators on the novel LNOSiC substrate were demonstrated, so as the ladder-type filter. Since part of the acoustic energy of the SH0 mode penetrates into the high-velocity SiC supporting substrate, the fabricated resonator exhibits a phase velocity of exceeding 5000 m/s. The ladder-type filter composed of the SH0 mode resonators with increased velocity shows a center frequency (f
c
) of 3.93 GHz, an insertion loss (IL) of 2.05 dB and a 3-dB fractional bandwidth (FBW) of 14.2%. The acoustic devices on LNOSiC heterogeneous substrate are very promising for high frequency and wideband 5G front-ends.