Tunable Electromechanical Coupling Coefficient of a Laterally Excited Bulk Wave Resonator with Composite Piezoelectric Film

• Published in: Micromachines (Basel) Vol. 13; no. 4; p. 641
• Main Authors: Xie, Ying, Liu, Yan, Liu, Jieyu, Wang, Lei, Liu, Wenjuan, Soon, Bo Woon, Cai, Yao, Sun, Chengliang
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 18-04-2022; MDPI
• Subjects: Boundary conditions; Composite materials; composite piezoelectric material; Coupling coefficients; Electric fields; Electrodes; electromechanical coupling coefficient \({K_{t}^{2}}\); filter; laterally excited bulk wave resonator (XBAR); Lithium niobates; Mathematical analysis; Piezoelectric films; Radio communications; Resonators; Silicon dioxide; Thin films; filter; laterally excited bulk wave resonator (XBAR); composite piezoelectric material; electromechanical coupling coefficient Kt2
• ISSN: 2072-666X; 2072-666X
• DOI: 10.3390/mi13040641

A resonator with an appropriate electromechanical coupling coefficient (Kt2) is crucial for filter applications in radio communication. In this paper, we present an effective method to tune the Kt2 of resonators by introducing different materials into a lithium niobate (LiNbO
) piezoelectric matrix. The effective piezoelectric coefficients e33eff and e15eff of composite materials with four different introduced materials were calculated. The results show that the e15eff of SiO
/LiNbO
composite piezoelectric material was mostly sensitive to an increase in the width of introduced SiO
material. Simultaneously, the simulation of a laterally excited bulk wave resonator (XBAR) with SiO
/LiNbO
composite material was also carried out to verify the change in the Kt2 originating from the variation in e15eff. The achievable n79 filter using the SiO
/LiNbO
composite material demonstrates the promising prospects of tuning Kt2 by introducing different materials into a LiNbO
piezoelectric matrix.