Title :
A high performance integrated DC SQUID magnetometer
Author :
Cantor, R. ; Enpuku, K. ; Ryhanen, T. ; Seppa, H.
Author_Institution :
Physikalisch-Tech. Bundesanstalt, Berlin, Germany
fDate :
3/1/1993 12:00:00 AM
Abstract :
The authors have carried out extensive mappings of the DC characteristics and flux noise of an integrated, DC superconducting quantum interference device (SQUID) magnetometer as functions of bias current and applied flux. The open-loop white flux noise at 1 kHz measured without flux modulation is Phi /sub n/<7*10/sup -7/ Phi /sub 0// square root Hz throughout a broad region of operation where the current-voltage and voltage-flux characteristics are smooth. The corresponding flux density noise B/sub n/<4 fT/ square root Hz. In addition, a recent model of the coupled DC SQUID was used to calculate the frequency-dependent impedance Z(f) seen by the Josephson junctions. The peaks observed in Z(f) are shown to be consistent with features in the current-voltage characteristics at high bias currents.<>
Keywords :
SQUIDs; electric impedance; electron device noise; magnetometers; superconducting integrated circuits; white noise; 1 kHz; DC characteristics; Josephson junctions; bias current; current-voltage characteristics; flux density noise; flux noise; frequency-dependent impedance; integrated DC SQUID magnetometer; open-loop white flux noise; voltage-flux characteristics; Current measurement; Frequency; Impedance; Interference; Noise measurement; SQUID magnetometers; Superconducting device noise; Superconducting devices; Voltage; White noise;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
