The use of (Double) relaxation oscillation SQUIDs as a sensor

Author

Van Duuren, M.J. ; Brons, G.C.S. ; Kattouw, H.E. ; Flokstra, J. ; Rogalla, H.

Author_Institution

Dept. of Appl. Phys., Twente Univ., Enschede, Netherlands

Volume

7

Issue

2

fYear

1997

fDate

6/1/1997 12:00:00 AM

Firstpage

3469

Lastpage

3472

Abstract

Relaxation Oscillation SQUIDs (ROSs) and Double Relaxation Oscillation SQUIDs (DROSs) are based on relaxation oscillations that are induced in hysteretic dc SQUIDs by an external L-R shunt. The relaxation frequency of a ROS varies with the applied flux /spl Phi/, whereas the output of a DROS is a dc voltage, with a typical flux-to-voltage transfer of /spl part/V//spl part//spl Phi//spl ap/1 mV//spl Phi//sub 0/. The flux-to-frequency response of several ROSs has been measured and compared with theory for frequencies up to 7 GHz. Various DROS designs-a multi-loop direct coupling DROS, a DROS with a washer type signal SQUID and a DROS with gradiometric signal SQUID-will be discussed in this paper. The integration of a DROS with a digital flux locked loop ("Smart DROS") will also be analyzed.

Keywords

SQUID magnetometers; relaxation oscillators; 7 GHz; LR shunt; digital flux locked loop; double relaxation oscillation SQUID; flux-to-frequency response; flux-to-voltage transfer; gradiometric signal; hysteretic DC SQUID; multi-loop direct coupling DROS; relaxation oscillation SQUID; sensor; smart DROS; washer type signal; Clocks; Crosstalk; Cryogenics; Frequency; Hysteresis; Magnetic flux; SQUIDs; Superconducting device noise; Temperature sensors; Voltage;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.622139

Filename

622139