Practical low-noise integrated dc superconducting quantum interference device magnetometer with additional positive feedback

Journal Article · Mon Jul 08 04:00:00 EDT 1991 · Applied Physics Letters; (USA)

DOI:https://doi.org/10.1063/1.105974· OSTI ID:5660853

Ryhaenen, T; Cantor, R; Drung, D; Koch, H ^[1]

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1. Physikalisch-Technische Bundesanstalt, Institut Berlin, Abbestrasse 10-12, D-1000 Berlin 10, Germany (DE)

We have designed and fabricated a low-noise dc superconducting quantum interference device (SQUID) magnetometer that is integrated on a 4{times}4 mm{sup 2} chip. The white flux noise of the magnetometer measured in a flux-locked-loop mode using simple, direct-coupled electronics with additional positive feedback (APF) is 6.4{times}10{sup {minus}7} {Phi}{sub 0}/{radical}Hz. The corresponding white flux density noise is 3.9 fT/{radical}Hz. The SQUID flux-to-voltage transfer function with APF is enhanced to 4.7 mV/{Phi}{sub 0} at the optimal working point, thereby significantly reducing the preamplifier contribution to the total noise. A maximum feedback field of 65 nT for frequencies up to 300 Hz and a maximum slew rate of 120 {mu}T/s at 300 Hz have been attained using a two-pole integrator.

• OSTI ID: 5660853
• Journal Information: Applied Physics Letters; (USA), Journal Name: Applied Physics Letters; (USA) Vol. 59:2; ISSN APPLA; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

426001* -- Engineering-- Superconducting Devices & Circuits-- (1990-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DESIGN
ELECTRONIC EQUIPMENT
EQUIPMENT
FEEDBACK
FLUXMETERS
MAGNETIC FLUX
MAGNETOMETERS
MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
SIGNAL-TO-NOISE RATIO
SQUID DEVICES
SUPERCONDUCTING DEVICES