Title :
DC-SQUID electronics based on the noise cancellation scheme
Author :
Kiviranta, M. ; Seppa, H.
Author_Institution :
VTT Autom. Meas. Technol., Espoo, Finland
fDate :
6/1/1995 12:00:00 AM
Abstract :
We have constructed a compact dc SQUID electronics unit, in which the noise of the room-temperature amplifier is measured by the SQUID and cancelled out. This makes it unnecessary to use a transformer and a modulation scheme to achieve noise matching between the SQUID and the amplifier. The electronics unit contains a PI/sup 3/2/-controller and it has demonstrated a bandwidth of 100 kHz, a 1.2 /spl mu//spl Phi//sub 0///spl radic/(Hz) white noise level and a 1/f noise corner of 0.3 Hz in a flux-locked loop mode. The design criteria for the noise-cancelled electronics are discussed, including the problem of excess noise.<>
Keywords :
1/f noise; SQUIDs; superconducting device noise; white noise; 1/f noise; 100 kHz; DC-SQUID electronics; PI/sup 3/2/-controller; flux-locked loop; noise cancellation; noise matching; room-temperature amplifier; white noise; Circuit noise; Coils; FETs; Magnetic flux; Magnetic noise; Noise cancellation; Noise measurement; SQUIDs; Temperature measurement; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
