Frequency synthesis from Cryogenic Sapphire Oscillator

Abstract

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. I.

Low Phase Noise Frequency Synthesis for Ultrastable $X$ -Band Oscillators

“…They also used regenerative frequency dividers to ensure low phase noise. The close-in phase noise in [11], outperform our results by around 3 dB at 1 Hz offset at 100 MHz, while our thermal noise floor is better by more than 25 dB, except at 10 GHz.…”

“…al. [11] used a CSO using WGH 15,0,0 mode which has a resonant frequency around 10 GHz. They also used regenerative frequency dividers to ensure low phase noise.…”