Evaluation of superconducting quantum interference devices interfaced with digital signal processing electronics for biomagnetic applications
Conference
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OSTI ID:10171486
The performance of a dc-SQUID magnetometer driven by both analog electronics and digital signal processors are investigated and compared for biomagnetic applications. Low-noise ( < 5 {mu} {Phi} {sub 0}/{radical}Hz at 1 Hz) dc-SQUIDs were fabricated by Conductus, Inc. using the all-refractory Nb/Al/Al{sub 2}O{sub 3}/Nb process on silicon substrates with on-chip modulation coils and integral washer damping resistors. A second-order gradiometer was magnetically coupled to the input coil of the SQUID to maximize the detected signal strength. The readout of this SQUID gradiometer was achieved using a conventional flux-locked loop (FLL) circuit to provide a linearized voltage output that was proportional to the flux applied to the SQUID. A shielded cylinder was constructed to house the magnetometer to reduce ambient field noise. To realize the digital feedback loop, the analog FLL is replaced except for the preamplifier by a digital signal processing board with dual 16-bit A/D and D/A converters. This approach shows several advantages over the analog scheme including operational flexibility, cost reduction, and possibly, the enhancement of dynamic ranges and slew rates.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10171486
- Report Number(s):
- LA-UR--94-2620; CONF-9410164--2; ON: DE94016186
- Country of Publication:
- United States
- Language:
- English
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