Methods of Zero Thermal Offset Compensation and Precision Measurements Using a Microvolt-level Josephson Voltage Standard

In order to enhance the accuracy of low-voltage measurement based on the double Josephson junction arrays on one chip developed at NIM, a method has been proposed for compensating thermal voltages on precision measurement leads, with the practical details. Better results have been obtained. The reading error of typical point e.g. at ±1 µV with a few nV smaller than before. When the system was built to be performed as an instrument like a digital voltmeter (DVM) to calibrate a dc reference, an optimized operation is presented to improve performance particularly for low-voltage measurement.