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Proceedings Paper

Noise study of gradiometer comprised of a Ketchen-type dc-SQUID with additional positive feedback (APF)
Author(s): Yooichi Takada; K. Kazami; G. Uehara; Hisashi Kado
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Paper Abstract

We investigated effective flux-to-voltage transfer function and flux noise characteristic corresponding to positive feedback parameter (beta) a on Ketchen-type dc-SQUID with additional positive feedback (APF) by comparing the experimental results with calculated results. The measurement and calculated results for the effective flux-to-voltage transfer function and white flux noise characteristic are in good agreement. We quantitatively obtained the white flux noise characteristic of dc-SQUID (dc-Superconducting Quantum Interference Device) with APF. As (beta) a approaches unity, the flux noise caused by preamplifier voltage noise is decreased and the flux noise caused by the intrinsic flux noise of dc-SQUID with APF is increased. We find that an optimum value of dc-SQUID with APF exists, determined by the trade-off between the flux noise caused by preamplifier voltage-noise and the intrinsic flux noise of dc- SQUID with APF.

Paper Details

Date Published: 2 July 1994
PDF: 9 pages
Proc. SPIE 2160, Superconductive Devices and Circuits, (2 July 1994); doi: 10.1117/12.181004
Show Author Affiliations
Yooichi Takada, Superconducting Sensor Lab. (Japan)
K. Kazami, Superconducting Sensor Lab. (Japan)
G. Uehara, Superconducting Sensor Lab. (Japan)
Hisashi Kado, Electrotechnical Lab. (Japan)


Published in SPIE Proceedings Vol. 2160:
Superconductive Devices and Circuits
Robert A. Buhrman; John T. Clarke; Ken Daly; Roger H. Koch; Jerome A. Luine; Randy W. Simon, Editor(s)

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