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Title: Investigation and optimization of low-frequency noise performance in readout electronics of dc superconducting quantum interference device

We investigated and optimized the low-frequency noise characteristics of a preamplifier used for readout of direct current superconducting quantum interference devices (SQUIDs). When the SQUID output was detected directly using a room-temperature low-voltage-noise preamplifier, the low-frequency noise of a SQUID system was found to be dominated by the input current noise of the preamplifiers in case of a large dynamic resistance of the SQUID. To reduce the current noise of the preamplifier in the low-frequency range, we investigated the dependence of total preamplifier noise on the collector current and source resistance. When the collector current was decreased from 8.4 mA to 3 mA in the preamplifier made of 3 parallel SSM2220 transistor pairs, the low-frequency total voltage noise of the preamplifier (at 0.1 Hz) decreased by about 3 times for a source resistance of 30 Ω whereas the white noise level remained nearly unchanged. Since the relative contribution of preamplifier's input voltage and current noise is different depending on the dynamic resistance or flux-to-voltage transfer of the SQUID, the results showed that the total noise of a SQUID system at low-frequency range can be improved significantly by optimizing the preamplifier circuit parameters, mainly the collector current in case of low-noisemore » bipolar transistor pairs.« less
Authors:
 [1] ;  [2] ; ;  [3] ;  [3] ;  [4]
  1. College of Instrumentation and Electrical Engineering, Jilin University, Changchun 130061 (China)
  2. (PGI-8), Forschungszentrum Jülich (FZJ), D-52425 Jülich (Germany)
  3. Peter Grünberg Institute (PGI-8), Forschungszentrum Jülich (FZJ), D-52425 Jülich (Germany)
  4. (Korea, Republic of)
Publication Date:
OSTI Identifier:
22308859
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 5; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; BACKGROUND NOISE; DIRECT CURRENT; ELECTRIC POTENTIAL; HZ RANGE; OPTIMIZATION; PERFORMANCE; PREAMPLIFIERS; READOUT SYSTEMS; SQUID DEVICES; TRANSISTORS