Stabilizing a SQUID current amplifier in high magnetic fields

V. Shingla, E. Kleinbaum, L. N. Pfeiffer, K. W. West, G. A. Csáthy

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

SQUID-based galvanometers are unstable when connected to sources exposed to strong magnetic fields. We present a SQUID-based current amplifier with a 17 fA (√Hz)-1 current noise, which is unconditionally stable with a source exposed to magnetic fields up to 10 T. Stability is achieved by inserting a four-pole low-pass filter between the source and the current amplifier. With this circuit, we demonstrate Johnson noise measurements below 1 K for source impedances in the kω range subjected to strong magnetic fields.

Original languageEnglish (US)
Article number105903
JournalMeasurement Science and Technology
Volume29
Issue number10
DOIs
StatePublished - Sep 14 2018
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Instrumentation
  • Engineering (miscellaneous)
  • Applied Mathematics

Keywords

  • dc SQUID
  • low noise current amplifier
  • two-dimensional electron gas

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