Analog phase-locked ceramic resonator oscillators

Abstract:

This study researched and analyzed the analog phase-locked Ceramic Resonator Oscillators(CRO) technology based on low-phase noise，high-clutter suppression techniques. The analog phase-locked frequency source and the phase-locked frequency source implemented by traditional methods，were compared and analyzed. Based on the analysis of the working principle of sampling phase detector，an implementation scheme for the analog phase-locked CRO was proposed. Highlighting the operating principle and parameters setting of loop filter circuit and the auto-capture circuit，a method was given to improve the output signal spurious suppression. The phase noise indicators of the designed analog phase-locked CRO，were difficult to be obtained using general phase-locked methods. The practical test result of the proposed scheme indicated that the phase noise of analog phase-locked CRO was very low(with output frequency of 3 GHz，the phase noise could be less than or equal to -115 dBc/Hz@10 kHz)，and the spurious suppression index also showed certain advantages(could be better than -70 dBc).