INTRINSIC AND AUTOMATED VOLTAGE CALIBRATIONS USING A JOSEPHSON ARRAY

摘要

Published algorithms for performing voltage calibrations with a Josephson array required knowledge of the unknown to within half of a voltage step and are not suitable for direct calibration of standard cells. This paper presents methods of calibration which provide automated setting of the array, recovery from non-synchronous operation and include special precautions for the direct calibration of standard cells. If an error is made in making the initial estimate of the reference being calibrated, then the resulting calibration may be in error by an integer number of voltage steps. Since the Josephson array is considered an intrinsic standard, then there must be a way to avoid incorrect steps. In this paper, techniques are presented which provide a procedure for detecting and correcting for this type of error. These methods eliminate the need for prior knowledge of a voltage reference or use of a calibrated precision voltmeter. These techniques depend upon the intrinsic voltage characteristics of the array and the linearity of the voltmeter used in the system.