着重讨论了汽泡型铷原子频标伺服电路中T型选频电路和RC移相电路的相位稳定性,分析了它们的附加相移波动影响整机频率稳定度的机理。为改进原子频标的性能,提出了一种用现场可编程门阵列(FPGA)实现对同步检测参考信号进行数字移相的技术。该基于FPGA的伺服电路的温度附加不稳定度为1×10-12/℃。 The phase stability of the T-type frequency-selecting circuit and the RC phase-shifting circuit in the bubble-type rubidium atomic frequency standard servo circuit is emphatically discussed. The mechanism of their additional phase-shift fluctuation affecting the frequency stability of the complete machine is analyzed. In order to improve the performance of atomic frequency standard, a technique of digital phase-shifting of synchronous detection reference signal with FPGA is proposed. The temperature instability of the FPGA-based servo circuit is 1 × 10-12 / ℃.