The Circuit Design Of Frequency Standard In Miniaturization Rubidium Atomic System

In the paper it was studied that the frequency synthesizer and multiplier and the phase modulation circuit of the rubidium atomic frequency standards (RAFS).The rubidium atomic frequency standards have been used in so many respects as navigation, communication, time transport and several science fields. At the same time, some field put forward request for it, such as the miniaturization of cubage and the simplification of structure.Firstly, we summarize the history of the development of the atomic frequency standards (AFS), in addition to the present status of the rubidium atomic frequency standard. Secondly, the characteristics of the control loop, the influence of the loop noise on the frequency stability were studied theoretically.In the rubidium atomic frequency standards, the instabilities of the frequency, modulation depth and the phase shift of the modulation have strong effects on the stability and accuracy of the output frequency. We adopt the indirect frequency modulation through a phase modulation of a 136Hz signal after it is integrated. Through this way we get a FM signal of low noise low distortion and high stability, and we can get the best modulation-depth by adjust the parameters.The function of synthesizer: obtain the special frequency for inspiriting rubidium atom transition .The input of synthesizer comes from VCO existed in system that is helpful for simplify the system and low the cost.The frequency multiplier is an important parts for the rubidium atomic frequency standards and its noise is the mostly source of the whole system's noise. The role of the frequency multiplier of the RAFS was analyzed. And we focus on the method and main point during the design stage to get low noise and high performance. The complete circuit and the test result are presented.