Comparison of ultra-stable radio frequency signals synthesized from independent secondary microwave frequency standards

TL;DR

This paper compares the phase noise and stability of ultra-stable radio frequency signals synthesized from independent cryogenic sapphire oscillators at multiple frequencies, demonstrating improved measurement accuracy and a new 1 GHz synthesizer design.

Contribution

It provides the first direct measurements of independent cryogenic oscillator-based signals at 100 MHz and 10 MHz, and introduces a novel 1 GHz synthesizer design using a phase-locked Crystek VCO.

Findings

Measured phase noise and stability data for 1 GHz, 100 MHz, and 10 MHz signals.

Demonstrated improved accuracy by using independent cryogenic oscillators.

Designed a new 1 GHz synthesizer with a cryogenic sapphire oscillator.

Abstract

The phase noise and frequency stability measurements of 1 GHz, 100 MHz, and 10 MHz signals are presented which have been synthesized from microwave cryogenic sapphire oscillators using ultra-low-vibration pulse-tube cryocooler technology. We present the measured data using independent cryogenic oscillators for the 100 MHz and 10 MHz synthesized signals, whereas previously we only estimated the expected results based on residual phase noise measurements, when only one cryogenic oscillator was available. In addition we present the design of a 1 GHz synthesizer using a Crystek voltage controlled oscillator phase locked to 1 GHz output derived from a cryogenic sapphire oscillator.