Low-noise SQUIDs with large transfer: two-stage SQUIDs based on DROSs

M. Podt, Jakob Flokstra, Horst Rogalla

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5 Citations (Scopus)


We have realized a two-stage integrated superconducting quantum interference device (SQUID) system with a closed loop bandwidth of 2.5 MHz, operated in a direct voltage readout mode. The corresponding flux slew rate was 1.3×105 Φ0/s and the measured white flux noise was 1.3 μΦ0/√Hz at 4.2 K. The system is based on a conventional dc SQUID with a double relaxation oscillation SQUID (DROS) as the second stage. Because of the large flux-to-voltage transfer, the sensitivity of the system is completely determined by the sensor SQUID and not by the DROS or the room-temperature preamplifier. Decreasing the Josephson junction area enables a further improvement of the sensitivity of the two-stage SQUID systems.
Original languageUndefined
Pages (from-to)225-228
JournalPhysica C
Issue numberPart 1
Publication statusPublished - 2002


  • Two-stage system
  • IR-74718
  • Superconducting device

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