Tilted Interdigital-transducer in NS-SAW Resonator for Transverse Mode Suppression

Multilayered shear-horizontal surface acoustic wave (SAW) resonators have attracted wide attention due to its high performance. However, the transverse modes appeared in spectrum will degrade the stability of the resonators. In this work, a tilted interdigital-transducer (IDT) method is proposed for a non-leaky stack SAW (NS-SAW) resonator using 30° YX-LiNbO
3
/SiO
2
/Si substrate to solve the above problem. In simulations, the IDT are optimized by designing different tilted angles. When the tilted angle is about 16°, the low-order transverse modes between resonant frequency (f
s
) and anti-resonant frequency (f
p
) are suppressed successfully. In particular, the high-order transverse modes between f
p
and the stopband frequency are also removed and the admittance plots become smoother. The measurement results verify that the tilted IDT method is effective to suppress the transverse modes of NS-SAW resonators.