J. Phys. III France
Volume 4, Numéro 4, April 1994
Page(s) 621 - 625
DOI: 10.1051/jp3:1994151
J. Phys. III France 4 (1994) 621-625

Realization of high $T_{\rm c}$ DC SQUID $_{\rm S}$. Characterization on a broad range of temperature

C. Dolabdjian, D. Robbes, C. Gunther, M. Lam Chok Sing, R. Desfeux and D. Bloyet

Laboratoire d'Electronique et d'Instrumentation, ISMRA, Boulevard du maréchal Juin, 14050 Caen Cedex, France

(Received 15 July 1993, revised 10 January 1994, accepted 17 January 1994)

The analysis of different types of Josephson junctions allows us to depict temperature dependences of the critical current $I_{\rm c}(T)$, the Josephson penetration depth $\lambda_{\rm J} (T)$ and main SQUID parameters. We show that a DC SQUID can operate on a broad range of temperature, with a current modulation equal to $\phi_0/L$ in the limit $\beta\gg 1$. The analysis is given within the RSJ model. For this purpose, the usual DC SQUID current biasing circuit is replaced by a voltage controlled system which detects current modulation. This voltage biasing is compatible with modulation technique usually applied to reduce the 1/f noise level of the junctions.

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