Progress in Superconductivity

한국초전도학회 (The Korean Superconductivity Society)
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64채널 DROS 심자도 시스템을 위한 검출 회로의 잡음 특성

Noise Characteristics of Readout Electronics for 64-Channel DROS Magnetocardiography System

  • Kim J. M. (Korea Research Institute of Standards and Science) ;
  • Kim K. D. (Korea Research Institute of Standards and Science) ;
  • Lee Y. H. (Korea Research Institute of Standards and Science) ;
  • Yu K. K. (Korea Research Institute of Standards and Science) ;
  • Kim K. W. (Korea Research Institute of Standards and Science) ;
  • Kwon H. C. (Korea Research Institute of Standards and Science) ;
  • Sasada Ichiro (Department of Applied Science for Electronics and Materials, Kyushu University)
  • 발행 : 2005.10.01
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초록

We have developed control electronics to operate flux-locked loop (FLL), and analog signal filters to process FLL outputs for 64-channel Double Relaxation Oscillation SQUID (DROS) magnetocardiography (MCG) system. Control electronics consisting of a preamplifier, an integrator, and a feedback, is compact and low-cost due to larger swing voltage and flux-to-voltage transfer coefficients of DROS than those of dc SQUIDs. Analog signal filter (ASF) serially chained with a high-pass filter having a cut-off frequency of 0.1 Hz, an amplifier having a gain of 100, a low-pass filter of 100 Hz, and a notch filter of 60 Hz makes FLL output suitable for MCG. The noise of a preamplifier in FLL control electronics is $7\;nV/{\surd}\;Hz$ at 1 Hz, $1.5\;nV/{\surd}\;Hz$ at 100 Hz that contributes $6\;fT/{\surd}\;Hz$ at 1 Hz, $1.3\;fT/{\surd}\;Hz$ at 100 Hz in readout electronics, and the noise of ASF electronics is $150\;{\mu}V/{\surd}\;Hz$ equivalent to $0.13\;fT/{\surd}\;Hz$ within the range of $1{\sim}100\;Hz$. When DROSs are connected to readout electronics inside a magnetically shielded room, the noise of 64-channel DROS system is $10\;fT/{\surd}\;Hz$ at 1 Hz, $5\;fT/{\surd}\;Hz$ at 100 Hz on the average, low enough to measure human MCG.

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