Research On Hybrid-compensation Technology For Reducing Acceleration Sensitivity Of TCXO

Almost all of the electronic equipments’ operating is dependent on frequency source, so the stability of frequency source directly affects the performance of electronic devices. With the advantages of light weight, small volume, high frequency stability, and low price, TCXO(Temperature Compensated Crystal Oscillator) is often used as a frequency reference in guided missile, satellite navigation receiver, wireless communications, and other electronic devices. Whether in aircraft or in communication equipment, TCXO will suffer from vibration or impact caused by the device itself and the outside world. Due to the acceleration effect of crystals itself, vibration or impact will lead to serious jitter, cause electronic equipment performance degradation. Therefore, how to reduce the acceleration sensitivity of TCXO becomes the core of this thesis.Thesis firstly introduced the acceleration effect of TCXO, discussed the feasibility of digital compensation technology for frequency shift of TCXO by voltage-controlled port. Then thesis researched the voltage-controlled characteristic of Pierce and Colpits circuits, which are the most common used oscillation circuits, by simulating. Thesis experimented on the voltage-controlled port of TCXO at last. In fact, either in the components or the resonant network will produce certain delay for compensation signal, but digital compensation technology requires high real-time. So, as the higher the vibration frequency, the bigger the compensation error caused by time delay, the poorer the digital compensation performance. In order to improve the frequency stability of TCXO under vibration, thesis put forward the method of mechanical cushion to compensate the higher frequency vibration, while voltage-controlled to compensate the lower frequency vibration. Designs the single-stage and two-stage vibration isolation structure, and then make a simulation of the two kinds of vibration isolation structure by MATLAB, the results show that mechanical cushion performance excellent when in high frequency vibration environment.Visibly, the combination of electronic compensation technology and mechanic cushion can effectively improve the phase noise of the crystal oscillator in wide frequency range. Thesis finally makes an experimental verification on TCXO with digital compensation technology, mechanical cushion, and hybrid-compensation technology respectively. Results show that the using of hybrid-compensation technology can effectively reduce the phase noise of crystal oscillator and extend the applicability of TCXO, for maintained averaging nearly 15 dB decay at 4g@(30~1k)Hz vibration.