Frequency synthesis from Cryogenic Sapphire Oscillator

In this paper we present several configurations enabling to obtain a low-noise 5 MHz signal from the 100 MHz delivered by the frequency synthesis of a Cryogenic Sapphire Oscillator. The residual single-sideband phase noise of several dividers is reported. Especially the noise of a custom built regenerative divider has been measured to be around ℒ5MHz(1 Hz) = −145 dBc/Hz. This performance is sufficient to measure the residual phase noise of an ultra-stable quartz crystal resonator using a carrier suppression system.