An integrated digital SQUID magnetometer with high sensitivity input

Radparvar, M.; Rylov, S.V.

doi:10.1109/77.403006

Cited by 13 publications

(2 citation statements)

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“…Digital SQUIDs are devices in which the sensor itself or, in multistage configurations, at least one of the following cryogenic stages is operated in a digital mode. There are various digital SQUID concepts reported in the literature: concepts involving room-temperature feedback electronics [32,59], latching Josephson logic [60][61][62][63][64][65][66][67], rapid single-fluxquantum (RSFQ) logic [68,69] or DROSs [57,58].…”

Section: Digital Squidsmentioning

confidence: 99%

High-T_cand low-T_cdc SQUID electronics

Drung

2003

Supercond. Sci. Technol.

125

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Superconducting quantum interference devices (SQUIDs) are commonly operated in a flux-locked loop (FLL). The SQUID electronics amplifies the small SQUID signal to an acceptable level without adding noise, and it linearizes the transfer function of the SQUID in order to provide sufficient dynamic range. In this paper, the fundamentals of SQUID readout are reviewed including a discussion of preamplifier noise. The basic FLL concepts, direct readout and flux modulation readout, are discussed both with dc bias and bias reversal. Alternative readout concepts such as additional positive feedback (APF), two-stage SQUIDs, SQUID series arrays, relaxation oscillation SQUIDs and digital SQUIDs are briefly described. The FLL dynamics are discussed on the basis of a simple model with finite loop delay. It is shown that with optimized SQUID electronics a system bandwidth of ≈18 MHz and a corresponding slew rate of ≈8 Φ0 µs−1 are possible. A novel FLL scheme involving a Smith predictor is presented which allows one to increase the FLL bandwidth to about 100 MHz. The theoretical predictions are experimentally checked using a high-speed SQUID electronics prototype with a small-signal bandwidth of 300 MHz. Methods for increasing the dynamic range of SQUID systems are described: flux-quanta counting and dynamic field compensation (DFC). With DFC, the residual magnetic field at the SQUID can be kept close to zero even if the device is moved in the Earth's field. Therefore, the noise level of a high-Tc magnetometer measured inside a magnetically shielded room (60 fT Hz−1/2 with a 1/f corner at 2 Hz) remained unchanged after moving the device in the magnetic field outside the room (60 µT dc plus 0.8 µT peak-to-peak power line interference).

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Section: Digital Squidsmentioning

confidence: 99%

High-T_cand low-T_cdc SQUID electronics

Drung

2003

Supercond. Sci. Technol.

125

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“…Another emerging technology of interest to SQUID NDE researchers is digital SQUIDs. Digital SQUIDs attempt to increase the dynamic range of SQUID systems by replacing the conventional room-temperature analogue electronics of the flux-locked loop with either a roomtemperature digital signal processor [138][139][140][141] (DSP) or an on-chip (4.2 K) integrated Josephson junction feedback circuit that involves flux counting [142][143][144]. The DSP circuits are being used successfully by a growing number of research groups.…”

Section: Squid Systems For Ndementioning

confidence: 99%

SQUIDs for nondestructive evaluation

Jenks

Sadeghi

Wikswo

1997

J. Phys. D: Appl. Phys.

138

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We attempt a comprehensive review of all published research in nondestructive evaluation (NDE) performed with the superconducting quantum interference device (SQUID) magnetometer since the first work was reported in the mid-1980s. The SQUID is the most sensitive detector of magnetic flux known. The energy sensitivity of the SQUID may make it the most sensitive detector of any kind. The research on SQUIDs for NDE is based on the promise of that sensitivity and on the various other desirable properties developed for SQUID instrumentation in biomagnetism and other fields. The sensitivity of SQUID instruments down to very low frequencies allows them to function as eddy-current sensors with unparalleled depth resolution, and to image the static magnetization of paramagnetic materials and the flow of near-dc corrosion currents. The wide dynamic range of the SQUID makes it possible to image defects in steel structures and to measure the magnetomechanical behaviour of ferromagnetic materials with high sensitivity. In the last decade SQUID instrumentation designed specifically for NDE has appeared and improved the spatial resolution of most work to roughly 1 mm, with promise of another order of magnitude improvement within the next five years. Algorithms for flaw detection and image deconvolution have begun to flourish. With many talented, industrious people in the field, the future of SQUID NDE looks bright, provided the crucial first niche can be found.

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Digital SQUID s

Febvre

2016

Digital Encyclopedia of Applied Physics

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The article contains sections titled: Introduction History of Digital SQUID s Recent Developments of Digital SQUID s An Application of Digital SQUID s for Studying Natural Hazards Prospects

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An integrated digital SQUID magnetometer with high sensitivity input

Cited by 13 publications

References 11 publications

High-T_cand low-T_cdc SQUID electronics

High-T_cand low-T_cdc SQUID electronics

SQUIDs for nondestructive evaluation

Digital SQUID s

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An integrated digital SQUID magnetometer with high sensitivity input

Cited by 13 publications

References 11 publications

High-Tcand low-Tcdc SQUID electronics

High-Tcand low-Tcdc SQUID electronics

SQUIDs for nondestructive evaluation

Digital SQUID s

Contact Info

Product

Resources

About

High-T_cand low-T_cdc SQUID electronics

High-T_cand low-T_cdc SQUID electronics