The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 10, 1992
Filed:
Aug. 10, 1990
Kai-Michael Ludeke, Hamburg, DE;
U.S. Philips Corporation, New York, NY (US);
Abstract
A method of suppressing current distribution noise in a DC SQUID comprising two Josephson junctions (12) in a superconducting current. This current distribution noise is caused by individual fluctuations of the critical currents of the two Josephson junctions used for measuring weak magnetic fields. A DC SQUID is connected to a device which comprises a control device (14) for generating a periodic bias current (I.sub.b), a modulation device (15) for generating a flux modulation via an induced AC current in the loop (11), and a signal detection device (17) for forming a mean output voltage (V.sub.ges). The polarity of the bias current (I.sub.B) is reversed by the control device (14) with the modulation frequency and a time shift of one quarter of the period duration of the modulation frequency, so that the SQUID assumes different bias states. In the case of suitably weighted signal detection in the signal detection device (17), the current distribution noise signals stemming from fluctuations of the critical currents eliminate one another in the signal sum taken over four bias states.