The pursuit for low cost and low phase noise synthesized signal sources: Theory & optimization

The performance of high frequency synthesizers is often tied to a lower-frequency reference oscillator, such as an oven-controlled crystal oscillator (OCXO), and enormous effort is often required to produce a stable microwave frequency synthesizer with ultra low phase noise. To demonstrate, a 10.24 GHz frequency synthesizer with OCXO reference source in conjunction with Möbius coupled DRO was developed, the measured phase noise is better than −138dBc/Hz @ 10 kHz offset with noise floor of −174 dBc. A hybrid approach shows great promise in achieving frequency synthesized microwave signals with low phase both close to and far from the carrier; the design path of reported 10.24 GHz synthesizer will be traced in the paper, and not limited to this frequency.