Measurement and analysis of thermal hysteresis in resonators and TCXOs

The resonators from anomalous TCXOs (temperature-compensated crystal oscillators) were temperature-cycled apart from the oscillators. Analysis of the resonator frequency versus temperature data, to account for thermal lag between the resonator and the external thermometer, showed that the inherent hysteresis of the resonator is much lower than that of the TCXO and has a different temperature dependence. A model was developed that accounts for both the normally encountered and anomalous thermal hysteresis. The model can separate apparent hysteresis from true hysteresis. This analysis can be used for allowing more accurate characterization and specification of TCXOs and resonators and for prediction of behavior under dynamic temperature conditions.<
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