Abstract: CPT atomic clock is widely used in communications, navigation, data transmission and many other fields for its small volume, low power and other advantages. In this paper, we design a microwave signal source with a central frequency of 4596 MHz in accordance with the requirement to microvave signal by the passive CPT Cs atomic clock through digital PLL technology.The signal source with circuit area of 30mm ×50mm and power less than 200 mW has a RF output power range of (-20~-5)dBm, and its output signal’s phase noise is consistent with the theory. Modulated ant a rate of 500 Hz, the signal source can meet the CPT Cs atomic clock’s requirement.

Key words: CPT, Cs atomic clock, PLL, RF multiplier, Phase noise, Microwave signal source