Noise study of gradiometer comprised of a Ketchen-type dc-SQUID with additional positive feedback (APF)
- 2 July 1994
- proceedings article
- Published by SPIE-Intl Soc Optical Eng
- p. 195-203
- https://doi.org/10.1117/12.181004
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.Keywords
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