VCO based design of low phase noise microwave frequency synthesizer

YIG Tune Oscillator (YTO) is a typical type of signal generation unit which is widely applied in the traditional wide band microwave frequency synthesizers. In recent years, the Voltage Controlled Oscillator (VCO) was developed as a substitution of YTO. Compared to YTO, VCO advances in terms of smaller physical size, lower cost, and shorter response time. Yet the phase noise of VCO is too high to be accepted in a few of actual applications, even it h as already been significantly improved. In this paper a series of low phase noise microwave frequency synthesizer design methods based on VCO are proposed. In addition, the test results in an actual experiment are provided, as single side band phase noise: -124.96 dBc/Hz at 10 GHz carrier with 10 kHz frequency offset.