Abstract: The crystal is the core component of the oven-controlled crystal oscillator,which needs to keep the temperature constant,and the great change of the external ambient temperature will surely affect the stability of the output frequency signal of the crystal.According to the working state and mechanism of the OCXO,a mathematical model of the heat transfer process in the steady state is established,the thermal stability of the crystal in high and low temperatures is investigated,and the influence of the output power of the power tubes on the temperature at the crystal in different ambient temperatures is emphasized,and the data during the actual operation of the OCXO are used for verification.The results show that the data obtained through simulation are basically consistent with the measured data;when the ambient temperatures are -40 ℃,25 ℃ and 70 ℃,respectively,the temperature at the stabilized crystal is 85 ℃,and the corresponding output power after stabilization of the power tubes is 3.95 W,1.42 W and 0.74 W.The output power of the power tubes is adjusted to make the temperature at the crystal constant.By adjusting the output power of the power tubes,the crystals can reach the preset temperature and keep it constant under extreme environments,so that the crystals can have high frequency stability and low phase noise level,and ensure the output of high-precision clock signals.

Key words: Oven-controlled crystal oscillator, Heat transfer property, Simulation and analysis, High and low temperature environment