DocumentCode :
1025401
Title :
A novel modulation technique for 1/f noise reduction in dc SQUIDs
Author :
Foglietti, V. ; Gallagher, W.J. ; Koch, R.H.
Author_Institution :
Istituto di Elettronica dello Stato Solido CNR, Roma, Italy
Volume :
23
Issue :
2
fYear :
1987
fDate :
3/1/1987 12:00:00 AM
Firstpage :
1150
Lastpage :
1153
Abstract :
We describe a novel modulation scheme for dc SQUIDs in flux locked loop applications that cancels the effects of Josephson junction critical current fluctuations. The scheme involves switching the SQUID between three states and detecting the output at the second harmonic of the modulation frequency. With this scheme we have achieved a ten fold reduction of the low frequency flux noise spectral density over that obtained with a conventional flux locked loop readout. A dc SQUID with a 20 pH inductance had a resultant noise spectral density of 10-12 
/Hz at 0.1 Hz, three times lower than the lowest flux noise previously reported for any SQUID system at this frequency.
/Hz at 0.1 Hz, three times lower than the lowest flux noise previously reported for any SQUID system at this frequency.Keywords :
Josephson device noise; Circuit noise; Critical current; Fluctuations; Frequency; Josephson junctions; Low-frequency noise; Noise level; Noise reduction; SQUIDs; Superconducting device noise;
fLanguage :
English
Journal_Title :
Magnetics, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9464
Type :
jour
DOI :
10.1109/TMAG.1987.1065126
Filename :
1065126
Link To Document :
