Research And Implementation Of Low G Sensitivity Oven Controlled Crystal Oscillator

With the development of modern communication technology,the higher performances of electronic devices products under vibration environment are required.As the clock frequency source of electronic equipment,quartz crystal oscillator is more susceptible to external vibration by the limited of structure and mechanical principle,which will affect the normal use of electronic equipment.Therefore,the g-sensitivity performance of the crystal oscillator is a short board for the normal use under vibration environment.The stability and reliability of the electronic device under vibration environment can be improved by reduce the g-sensitivity of crystal oscillator.In recent years,developed countries have strengthened the technical blockade on military and communication fields,crystal oscillators with excellent g-sensitivity performance have been placed on the regulatory list.It restricted the development of China's communication technology.Therefore,this paper focuses on develop a low g-sensitivity crystal oscillator.During the development of low g-sensitivity crystal oscillator,first we introduced the principle and related calculation methods of crystal resonators.Then we talked about the main oscillator circuit and the temperature control system of the oscillator.After that,we introduced the principle of crystal g-sensitivity and deduced the measurement method of g-sensitivity.We introduced a calculation method with more evaluation accuracy,then writed software to collect data and calculate the g-sensitivity automatically.Based on these works,we presented the methods of improvement of g-sensitivityThe crystal resonator is the most susceptible part in the crystal oscillator under vibration environments.The improvement of the crystal resonator can improve the performance of the crystal oscillator fundamentally.First,we calculated the structural parameters of two bases,the calculation showed the TO base has better g-sensitivity.Second,we analyze the influence of the value of the curvature and the center deviation to g-sensitivity,after that,we choosed the best curvature and found better method to get better surface.Third,we had done some jobs on coating method and the coating rate to get better electrodes.After these improvements,the g-sensitivity of crystal oscillator decreased three times.The vibration isolation part can weaken the amplitude of external vibration.We analyzed the vibration isolation model,and simulation the rubber material wih finite element method.We designed one rubber vibration isolation structure by analyze the effect on g-sensitivity with different density,Young's modulus and structural design.The phase noise test under vaberation found that this structure weaken the amplitude of external vibration in high frequency.We monitored the external vibration situation by using acceleration sensor and calculated the reverse compensation voltage by microcontroller.Then we added it to the VC part of the crystal oscillator to realize the vibration compensation effect.Through these three aspects of work,we designed a low g-sensitivity crystal oscillator.The g-sensitivity of this crystal oscillator is better than 0.16ppb/g in the range of 0 Hz to 2 kHz,and better than 0.02 ppb/g in the range of 500 Hz to 1 kHz.We achieved the goal and the performance of this crystal oscillator reached international level.