Phase noise analysis of the sapphire loaded superconducting niobium cavity oscillator

Author

Tobar, Michael E. ; Blair, David G.

Author_Institution

Dept. of Phys., Western Australia Univ., Nedlands, WA, Australia

Volume

42

Issue

2

fYear

1994

fDate

2/1/1994 12:00:00 AM

Firstpage

344

Lastpage

347

Abstract

Measured phase noise of two GaAs FET amplifiers and a varactor phase shifter at 9.7 GHz reveal that optimum bias conditions change when cooling from room to liquid helium temperatures. This understanding enables optimisation of the electronic noise in an all cryogenic tunable sapphire loaded superconducting cavity (SLOSC) X-band loop oscillator. The measured phase noise was limited by vibrations of the tuning mechanism. In a fixed frequency SLOSC oscillator the phase noise was limited by the amplifier noise, and has been measured to be -140 dBc/Hz at 1 kHz from the unfiltered port of the loop oscillator. Comparison of component and oscillator phase noise allows us to calculate the phase noise at the filtered port to be -175 dBc/Hz at 1 kHz offset

Keywords

cavity resonators; electron device noise; microwave oscillators; niobium; sapphire; solid-state microwave circuits; superconducting microwave devices; tuning; 9.7 GHz; Al₂O₃; GaAs; GaAs FET amplifiers; Nb; SHF; X-band loop oscillator; amplifier noise; electronic noise; liquid helium temperatures; optimum bias conditions; phase noise analysis; sapphire loaded cavity; superconducting Nb cavity oscillator; tuning mechanism; varactor phase shifter; FETs; Gallium arsenide; Niobium; Noise measurement; Oscillators; Phase measurement; Phase noise; Superconducting device noise; Varactors; Vibration measurement;

fLanguage

English

Journal_Title

Microwave Theory and Techniques, IEEE Transactions on

Publisher

ieee

ISSN

0018-9480

Type

jour

DOI

10.1109/22.275269

Filename

275269