Title :
Compact readout electronics for 62-channel DROS magnetocardiogram system
Author :
Kim, Jin-Mok ; Lee, Yong-Ho ; Kim, Kiwoong ; Kwon, Hyukchan ; Park, Yong-Ki ; Sasada, Ichiro
Author_Institution :
Korea Res. Inst. of Stand. & Sci., Daejeon, South Korea
fDate :
6/1/2005 12:00:00 AM
Abstract :
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 μΦo/√Hz or 0.6 fT/√Hz at 100 Hz, low enough to measure MCG fields.
Keywords :
SQUID magnetometers; biomedical electronics; computerised instrumentation; magnetocardiography; readout electronics; 62-channel DROS magnetocardiogram system; DROS gradiometer; biomagnetism; biomedical electronics; compact readout electronics; computerised instrumentation; double relaxation oscillation SQUIDs; low-cost SQUID electronics; magnetocardiogram field detection; Automatic control; Circuits; Computer interfaces; Filters; Frequency locked loops; Hardware; Preamplifiers; Readout electronics; SQUIDs; White noise; Biomagnetism; DROS; FLL; MCG; SQUID; flux-locked loop; magnetocardiogram;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
DOI :
10.1109/TASC.2005.849982
