Abstract
Resonators manufactured on Ca3TaGa3Si2O14 single crystals (CTGS) operating in a thickness shear mode were investigated. The frequency temperature characteristics of the rotated Y-cut based resonators were measured. The resonators operated at the crystal elements with angle cut −21°20' have frequency deviation less than 120 ppm in the operating temperature range from −60 up to 85°C. The temperature coefficient of frequency of the second order is close to −0.022 2 ppm/°C . It is shown that maintaining turnover point of the frequency temperature characteristic within the range of ±1 °C requires accuracy of the crystal element manufacturing not worse than ±1.5 angular minutes for resonators with Ag electrodes. The dependence of the Bechmann’s number on electrode thickness was calculated. It was discovered that for Ag electrode coating with electrode thickness of 200 nm, the single- response characteristic of the resonator can be obtained if the electrode size ( l ) does not exceed 12 thicknesses of the crystal element. With the limiting value of the relative electrode size equaling lx /t =12.3, the relative resonance interval is 1%, while the capacitance ratio is 47 units.
Conclusion
Resonators on CTGS single crystals operating in the fundamental mode of thickness shear vibration were investigated. On (YZw) –21°20' cut in operating temperature range from –60 up to 85°C, the resonance frequency deviation of less than 120 ppm was obtained. The TCF(2) is close to – 2 0.022 ppm/°C . It was shown that for resonators with Ag electrodes, maintaining extremum point temperature of the temperature- frequency characteristic within the range of ±1 °C requires crystal element manufacturing accuracy not worse than ±1.5 angular minutes. The dependence of the Bechmann’s number on electrode thickness was calculated. It was discovered that for Ag electrode coating with the thickness of 200 nm, the single response resonator can be obtained if the electrode size (lx) does not exceed twelve thicknesses (t) of the crystal element. With the limiting value of the relative electrode size equaling lx /t =12.3, the relative resonance interval is 1%, while the capacitance ratio is 47 units.
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