Capability of LiTaO3/Quartz HAL SAW Resonators Confirmed by Simulation and Measurement

This paper reports hetero acoustic layer (HAL) surface acoustic wave (SAW) resonators using a thin LiTaO
₃
(LT) plate with negative TCF and a quartz substrate with positive TCF. In the previous study, a high impedance (Z) ratio (82 dB), an excellent temperature coefficient of frequency (TCF: 2 ppm/°C), and spurious-free characteristic up to 14 GHz were demonstrated. In this study, two kinds of LT/ quartz HAL SAW resonators with different wavelengths of interdigital transducer (IDT) were fabricated, and measured results were compared with simulated ones. The measured bandwidths (BWs) roughly agreed with the simulated ones. Although many measured values of Z ratios are lower than the simulated ones, the best Z ratios among them are similar to the simulated ones. This result is reasonable taking account of the imperfectness of laboratory-level fabrication, and suggests that the simulation in this study well predicts the performance of real devices.