The Border Effect Of Precision Crystal Oscillator And Its Application

This thesis is mainly for the study of the border effect of crystal oscillator and its related characteristics.Border effect is a new theory, through its rational application, can improve the accuracy of frequency device.For crystal oscillator, Since the border of its oscillation frequency ambiguity region has high stability, therefore, the use of the edge effects of crystal oscillator can improve its performance.First, this thesis start with the physical characteristics of the crystal oscillator and its influencing factors, analyzed crystal oscillator’s working principle and its important components,and studied its aging drift characteristic and phase noise characteristic in detail.For crystal oscillator’s aging drift characteristic, analyzed its mechanism and its influencing factors,and then describes its characterization methods.By studying the traditional method of aging drift compensation, we presented a crystal oscillator automatic aging drift compensation scheme that is mainly controlled by an MCU.Compared to the uncompensated crystal oscillator,its day aging rate is about four times lower than before.For the phase noise characteristic of the crystal oscillator,this thesis elaborated its electrical noise, amplifier noise and resonance circuit noise and their respective causes.We Analyzed the mechanism of crystal oscillator’s phase noise characteristic and then discovered a method to reduce it.Through the study and improvement of Oven-controlled crystal oscillator’s temperature control circuit and oscillation circuit, we designed a good performance low phase noise crystal oscillator which index is -97dBc/Hz@1Hz,-128dBc/Hz@10Hz,-159dBc/Hz@1kHz.By the study of these two characteristics,laid a good foundation for our study of the border effect of crystal oscillator.Finally, this thesis described and analyzed the border effect in detail,and then studied the border effect of crystal oscillator and its application in depth.By Replacing an OCXO’s LC resonator filter which is used for frequency selection and filtering with a higher quality factor AT-cut crystal resonator,and compressing the oscillator resonance width to the border of its ambiguity region,can improve the equivalent quality factor of the oscillator.The experiment showed the phase noise of the OCXO that is improved by the use of its edge effect reduced 5dBc/Hz,and day aging rate decreased about 4 times.