晶体振荡器的频率稳定度和老化特性研究

Research on aging and frequency stability of crystal oscillator

晶体振荡器频率稳定度从其瞬态一直到接近于1s都是按照1/τ的规律变化,表现出典型的相位控制特征,但由于老化和低频噪声等影响,其频率稳定度在较长的取样时间内不会改进甚至变坏。原子钟输出信号是被锁定的晶体振荡器的信号,被动型原子钟采用锁频机制,其频率稳定度随着取样时间按照1/τ^(1/2)的规律变化。原子频标和晶体振荡器作为装置的频率稳定度实现的基础,形成了1/τ变化规律的频率稳定度的本底基础线。用精度更高的相位控制代替频率控制,可以使原子钟稳定度变化保持1/τ的规律。谐振器两端相移特性反映了晶体谐振参数的变化。晶体振荡器长期指标的改进,需要利用包括伴随着振荡器频率变化而发生的相关谐振参数与频率变化的相关性,发展数字化、等效晶体谐振参数检测、反馈控制以及老化补偿结合的方法。

Abstract： The frequency stability of crystal oscillator varies from its transient state to nearly one second in accordance with the rule of 1/τ,characterized by its typical phase control. Due to the influence of aging and low-frequency noise, the stability index of the frequency will not be improved or even worse in the longer sampling time. The output signal of an atomic clock is actually the signal of a controlled crystal oscillator. Passive atomic clock uses the locking mechanism, the stability of frequency change with the sampling time is in accordance with the 1/τ1/2 rules. These atomic standards and crystal oscillators are fully integrated in the system,as a basis for frequency stability index device, forming the frequency stability of the base line variation of 1/τ. Replacing frequency control with more precise phase control can keep the stability changes of 1/τ rules. The phase shift characteristic of the resonator reflects the change of crystal resonance parameters. Long term index of crystal oscillator can be improved by capturing relationship of the resonant parameters and the oscillator frequency, and combining the digitization process, the detection of the equivalent resonant parameters of the crystal, the feedback control and the compensation of the aging. Key words： crystal oscillator ; frequency stability ; resonance parameters ; phase control