小型化铷原子频标数字锁频环路设计与实现

Design and Realization of a Frequency Lock Loop Circuit for a Miniaturized Rubidium Atomic Frequency Standard

设计并实现了一种用于铷原子频标的小型化锁频环路。采用数字锁相倍频技术，实现了10MHz信号的45．5645833次倍频。再经过一级15次倍频后获得频率为6834．6875MHz的铷原子频标微波探寻信号。通过数字电路技术实现了455．645833MHz信号的小调频。测量并分析了455．645833MHz信号的相位噪声，结果表明电路系统对铷频标频率稳定度的贡献为3．2×10^-12τ^-1/2。测量-rN用该电路得到的铷频标的短期频率稳定度，结果为5×10^-12τ^-1/2（1s≤r≤100s），明显高于一般商品小型化铷原子频标。

A frequency-locked loop （FLL） circuit was designed and realized for a miniaturized high performance rubidium atomic frequency standard （RAFS）. The 10 MHz signal from a VCXO was transformed into the microwave interrogation signal with frequency of 6 834. 687 5 MHz by a 45. 564 583 3 multiplier and a consequent 15 one. The 455. 645 833 multiplier was designed by using the digital phase-locked technique. The frequency modulation of the interrogation signal was realized in the 455. 645 833 MHz signal. The phase noise of the signal was measured and analyzed. Results showed that the fractional stability of the microwave signal is in a level of 3.2×10^-12τ^-1/2. The short-term frequency stability of a RAFS containing the FLL circuit was tested, and a result of 5×10^-12τ^-1/2 （1s≤r≤100s） was obtained. This result is obviously better than that of an average commercial RAFS.