Wideband Surface Acoustic Wave Resonator with Good Temperature Stability Using LiNbO3 and Glass with Low Coefficient of Thermal Expansion

Low temperature coefficient of frequency (TCF) and high Quality (Q) factor are important for surface acoustic wave (SAW) device in increasingly busy frequency bands. We realized near-zero TCF in a LiTaO
3
(LT) based resonator, but the bandwidth (BW) was narrow. In this work, we combine LN and a glass with a low coefficient of thermal expansion (CTE) to realize a SAW resonator with large BW, low TCF and high impedance ratio (Z-ratio) simultaneously. The measured Zratio and BW are as high as 80.9 dB and 13.2%, respectively. The TCF reaches -22.5 ppm/℃ at f
a
when LN thickness is 0.156λ (λ is wavelength), which is the best level ever reported for resonators with similar BW.