High frequency ac bias for direct-coupled dc superconducting quantum interference device readout electronics

A high frequency ac-bias technique for direct-coupled readout electronics, for high temperature dc superconducting quantum interference devices (HTc dc SQUIDs), is presented. The method was tested for ac-bias frequencies between 2 and 10 MHz on different HTc dc SQUIDs. The minimum white flux-noise l...

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Bibliographic Details
Published in:Review of scientific instruments 2003-12, Vol.74 (12), p.5189-5193
Main Authors: Oukhanski, N., Schultze, V., IJsselsteijn, R. P. J., Meyer, H.-G.
Format: Article
Language:English
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Summary:A high frequency ac-bias technique for direct-coupled readout electronics, for high temperature dc superconducting quantum interference devices (HTc dc SQUIDs), is presented. The method was tested for ac-bias frequencies between 2 and 10 MHz on different HTc dc SQUIDs. The minimum white flux-noise level of 9.5 μΦ 0 / Hz 1/2 , corresponding to a noise limited magnetic field resolution of 24  fT/Hz 1/2 , was achieved with a HTc dc SQUID with a maximum voltage swing of 64 μV pp and an ac-bias frequency of about 7.7 MHz. A maximum system dynamic range of 156 dB (±600 Φ 0 ) in the white noise frequency region was achieved for this sensor. For various HTc dc SQUID magnetometers a bandwidth of between 1.6 and 4 MHz was measured. The slew rates were in the range of 1–2  M Φ 0 / s for several HTc dc SQUIDs.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.1622982