基准振荡器相位噪声对载波锁相环的影响

Impact of Phase Noise in Reference Oscillator on PLL

扩频接收机中的锁相跟踪环路噪声带宽受环路输入信号的各种内部和外部噪声误差的制约,在环路滤波器噪声带宽很窄的条件下,接收机基准振荡器的相位噪声对PLL环路的影响不能忽略。根据基准振荡器相位噪声功率谱密度的度量公式,考虑利用二阶锁相环的情况下,推导出基准振荡器的阿仑偏差与环路滤波器噪声带宽的关系,确定在跟踪接收机设计中,采用高频率稳定度的恒温晶振作为基准振荡器,可以获得较窄的环路噪声带宽,从而提高跟踪的稳定性和测量精度。

The tracking PLL noise bandwidth is constrained by a variety of signal noise sources in navigation receiver, under the condition of narrow noise bandwidth in the loop filter, the impact of phase noise in reference oscillator of receiver on the PLL loop can not be ignored. According to the benchmark of phase noise power spectral density for reference oscillator with the use of second - order phase - locked loop, the relationship between Alan deviation in reference oscillator and loop filter noise bandwidth is derived, furthermore, enhancing the stability and accuracy of the tracking can be made by narrow loop noise bandwidth in the design of tracking receiver using OCXO with higher - frequency stability.