Comparative study of piston mode designs for temperature-compensated surface acoustic wave resonators using SiO₂/LiNbO₃ structure

Abstract

This paper compares three different piston mode designs for temperature-compensated surface acoustic wave (TC-SAW) resonators using SiO2/LiNbO3 structure. It was shown that in rough approximation, phase shift given by extra elements for the piston mode operation is determined by their total mass. Thus, the hammer head design without additional metal layers does not work properly when the SiO2 layer is thick due to insufficient mass. On the other hand, piston mode designs using metal dots or stripes is effective to suppress the transverse mode resonances even when the SiO2 layer is thick. Although larger metal thickness is preferable for the wideband operation, it also makes the split of main resonance. Thus, the optimal metal thickness can be found from this trade off, and then the optimal metal width can be found to achieve good transverse mode suppression.

S0-like SAW mode resonator on LiNbO3/SiO2/SiC structure

“…The authors' group reported that the "hammerhead" design is effective for the layered SAW structure employing a 42-LT thin plate 36) where the SAW slowness curve is almost flat while the "metal dot" design for the temperature compensated (TC) SAW structure on 128°YX-LiNbO 3 where the SAW slowness curve is convex. [32][33][34][35] The SAW slowness curve is also convex for the present case. Insufficient transverse mode suppression may be due to asymmetry of the SAW slowness curve along the SAW propagation direction due to nonzero α.…”

“…First, it is shown that the dummy electrodes are not necessary in this case. Then, two kinds of piston design [32][33][34][35] are applied for the transverse suppression, and their effectiveness is discussed.…”

SAW velocity reduction and spurious modes suppression on the layer structure

“…12 is applied to enhance the energy confinement. "Hammer-heads" [28][29][30] are given at the side edges of the aperture region for the piston mode operation.…”

“…Next, suppression of transverse mode resonances and lateral leakage is studied. It is shown that the double busbar structure 27) offers Q enhancement through good lateral energy confinement, and its combination with the piston design [28][29][30] also gives good transverse mode suppression. Furthermore, discussions are extended to a strong spurious resonance that appears near the anti-resonance.…”

Resonance properties of shear-horizontal surface acoustic waves on Ca3TaGa3Si2O14 at room and high temperatures

“…Recently, many studies have been reported related to various SAW device applications. [1][2][3][4][5][6] SAWs propagate by trapping their energy in the vicinity of the surface and are excited by applying a high-frequency electric field to a piezoelectric substrate with an interdigital transducer (IDT) fabricated on it. Moreover, SAW-based sensors are utilized as maintenance-free sensors because they can wirelessly measure temperature, pressure and strain without the need for batteries.…”