Compact readout electronics for 62-channel DROS magnetocardiogram system

Jin Mok Kim, Yong Ho Lee, Kiwoong Kim, Hyukchan Kwon, Yong Ki Park, Ichiro Sasada

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Compact and low-cost SQUID electronics to operate double relaxation oscillation SQUIDs (DROSs) has been constructed for detecting magnetocardiogram (MCG) fields. SQUID electronics consists of low-noise preamplifier with a white noise of 0.6 nV/√Hz, flux-locked loop (FLL) circuit with auto-reset, and interface circuit to control FLL using 3 digital lines from a computer. The automatic control software adjusts SQUID parameters to the optimum operating condition within 15 seconds for 62 channels. Outputs of FLL circuits are passed through the hardware filter box to the 64-channel data acquisition board. Each SQUID electronics for FLL and digital control is built together on a printed circuit board of 45 mm × 95 mm. When SQUID electronics is connected to DROS gradiometer with typical flux-to-voltage transfers of 1 mV/Φo, the noise contribution of FLL circuit is about 0.6 μ&Φo/√Hz or 0.6 fT/√Hz at 100 Hz, low enough to measure MCG fields.

Original languageEnglish
Pages (from-to)644-647
Number of pages4
JournalIEEE Transactions on Applied Superconductivity
Issue number2 PART I
Publication statusPublished - Jun 2005

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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