Ultra-low-noise regenerative frequency divider for high-spectral-purity RF signal generation

Abstract

Abstract-We implement an ultra-low-noise frequency divider chain from 8 GHz to 5 MHz that utilizes custom-built regenerative frequency divide-by-2 circuits. The single-sideband (SSB) residual phase-noise of this regenerative divider at 5 MHz output is -163 dBc/Hz at 10 Hz offset frequency. This level is achieved with custom-built mixers that use 2N2222A bipolar junction transistors in a conventional double-balanced diode ring. We report absolute phase-noise of radio-frequency (RF) signals at 10 MHz and 5 MHz obtained by dividing an 8 GHz signal generated from ultra-stable optical comb-based frequency division. The absolute SSB phase-noise for a 10 MHz and 5 MHz signal at 1 Hz offset is -143 dBc/Hz and -150 dBc/Hz, and at 100 kHz offset is -174 dBc/Hz and -177 dBc/Hz, respectively.

Spiral resonators for on-chip laser frequency stabilization

“…This is a level that is already competitive with the state-of-the-art oven-controlled crystal oscillators, and the basic architecture to accomplish this has been demonstrated with the combination of laboratory frequency combs and electronic division41. It is intriguing to consider that the spiral cavity demonstrated here could be the frequency reference for a chip-integrated platform, that together with advances in microcomb technology4243 would ultimately provide broad-bandwidth synthesis of low-phase-noise signals from the optical to the RF.…”

Frequency synthesis from Cryogenic Sapphire Oscillator

“…Its low level gain is 15 dB and its output power at the 1 dB compression point is around 18 dBm at 5 MHz. In the RD loop the amplifier saturates [18], [22]. The output signal power is +12 dBm.…”