A 4.596GHz low phase-noise VCO for cesium atomic frequency standard

With the progress of science and technology, astronomy, navigation, space travel and other fields need higher precision time and frequency standards to provide a strong guarantee. Atomic clocks based on coherent population trapping (CPT) can not only meet the accuracy requirement, but also be improved in the direction of miniaturization and low power consumption. Cesium atomic clocks have superiority in accuracy and stability comparing with others, and their performance largely depends on the internal voltage controlled oscillator (VCO). In this paper, a small volume and low phase noise VCO circuit used for cesium atomic clocks is designed with the negative resistance analysis method first, and then optimized with the virtual-ground technique. Test results show that, at the frequency of 4.596GHz, the phase noise is -56.23dBc/Hz@1kHz, and the output power is 0.57dBm, which meet the requirements of cesium atomic clocks.