Acceleration Compensation Crystal Oscillator Study

The high frequency crystal oscillator is the critical part of the electronic apparatus. As the reference frequency source, it is widely used in communication, navigation, radar, measure instruments etc…Thus, it is called the"heart"of the above equipments.When it is working, the crystal would be affected by vibration, centrifugal force, etc, or say be affected by acceleration. At present, as the quick progressing of the electronic technology, the problem of diminishing this affection becomes quite important.In order to heighten the frequency stability of oscillator when it is working under acceleration, a lot of research has been done. Various compensation methods have been brought up, these methods could be concluded into two classes: passive and active. Passive methods include using new-cut oscillator, improving the crystal fit technology, matching dual-crystal, and vibrate separation, etc. Active methods include using accelerate sensor and some feedback.In this paper, an improved high frequency and low phase noise compensation approach based MCU control is presented. A 12.8MHz acceleration compensation crystal oscillator is designed with this approach. It uses acceleration sensor to detect the acceleration signal, then programming in MCU to control the frequency stability. By experiments, this oscillator achieves the phase noise level of -135dBc/Hz @1kHz, in condition that vibration frequency is between 200 and 800Hz, the amplitude is 1g.