A wide-band double-PLL microwave frequency synthesizer

We describe a wideband microwave frequency synthesizer operating from 2 to 18 GHz. The synthesizer is based on a YIG-tuned oscillator (YTO), a sampling phase detector (SPD) working as a sub-harmonically pumped mixer and a double PLL integrated circuit for stabilizing the frequencies of a local oscillator and the YTO. The whole circuitry is supervised by a microcontroller. For this design, we discuss the underlying issues that regard flexible frequency control and optimization of the phase noise performance.