Title :
Radio frequency bias current scheme for dc superconducting quantum interference device
Author :
Zhang, Y. ; He, D.F. ; Wolters, N. ; Otto, R. ; Barthels, K. ; Zeng, X.H. ; Yi, H.R. ; Krause, H.-J. ; Braginski, A.I. ; Faley, M.J.
Author_Institution :
Inst. fur Schicht- und Ionentech., Forschungszentrum Julich GmbH, Germany
fDate :
6/1/1999 12:00:00 AM
Abstract :
We have developed a radio frequency bias current scheme with reversal frequency up to 50 MHz for dc superconducting quantum interference devices (SQUIDs). The SQUID and the readout electronics, were connected via a quarter wavelength (/spl lambda//4) transmission line. This transmission line not only transported the SQUID signal, but also served as the resonant matching circuit. For a dc SQUID of inductance 115 pH (loop size 75/spl times/75 /spl mu/m/sup 2/), we measured a flux noise of 33 /spl mu//spl phi//sub 0///spl radic/Hz at 77 K in the flux locked loop configuration. The corner frequency of 1/f noise was less than 0.5 Hz.
Keywords :
1/f noise; SQUIDs; readout electronics; superconducting device noise; superconducting transmission lines; 1/f noise; 50 MHz; 77 K; DC SQUID; RF bias current; flux locked loop; flux noise; inductance; readout electronics; resonant matching circuit; transmission line; Circuit noise; Distributed parameter circuits; Radio frequency; Radiofrequency interference; Readout electronics; Resonance; SQUIDs; Superconducting device noise; Superconducting devices; Superconducting transmission lines;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
