Resistively shunted dc SQUID coupled to an input coil

Journal Article · Sat Mar 01 00:00:00 EST 1986 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.336436· OSTI ID:6300853

Enpuku, K; Yoshida, K

A theoretical study has been made of a resistively shunted dc SQUID coupled to an input coil. The effect of a circulating current is taken into account. An analytical expression for the circulating current is obtained by replacing the nonlinear Josephson current with a linear ac current generator. It is shown that in the conventional SQUID, the circulating current changes considerably the input impedance seen from the input coil, and that the input impedance becomes nonlinear. As a result, previous optimization conditions of amplifiers and magnetometers, which were obtained by neglecting the circulating current, lead to errors amounting to 40%. In the case of a resistively shunted SQUID, where a damping resistance is attached in parallel with an inductance of the SQUID, it is shown that the circulating current can be suppressed significantly with the damping resistance. Therefore, the change of the input impedance caused by the circulating current can be eliminated in this case.

• Research Organization: Department of Electronics, Kyushu University 36, Fukuoka 812, Japan
• OSTI ID: 6300853
• Journal Information: J. Appl. Phys.; (United States), Vol. 59:5
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
SQUID DEVICES
ELECTRIC CURRENTS
PERFORMANCE
ANALYTICAL SOLUTION
ELECTRIC IMPEDANCE
ERRORS
JOSEPHSON JUNCTIONS
THEORETICAL DATA
CURRENTS
DATA
ELECTRONIC EQUIPMENT
EQUIPMENT
FLUXMETERS
IMPEDANCE
INFORMATION
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MEASURING INSTRUMENTS
MICROWAVE EQUIPMENT
NUMERICAL DATA
SUPERCONDUCTING DEVICES
SUPERCONDUCTING JUNCTIONS
420201* - Engineering- Cryogenic Equipment & Devices