Study on applicability of dielectric strips for transverse mode suppression of I.H.P. SAW resonators using low cut LiTaO₃ plate

Abstract This paper discusses the applicability of the dielectric (SiO 2 ) strips for the transverse mode suppression of incredible high-performance surface acoustic wave (SAW) resonators employing a thin LiTaO 3 (LT) plate with small LT cut angle θ . Proper setting of the metallization ratio (MR) makes the SAW slowness curves curvature small and electromechanical coupling factor ( k 2 ) large. When MR is set at 0.35, the transverse modes are suppressed well even when θ is reduced to 24° and degradation of the Bode Q is not obvious, although achievable k 2 is a little lower than the case of MR = 0.5. When MR is set at 0.5, although the transverse mode can be suppressed when θ is larger than 34°, degradation of the Bode Q becomes obvious with the decrease of θ .