Improved dual Josephson voltage standard potentiometer for high precision arbitrary resistance ratio measurements

This work presents an improved and much more flexible setup of the dual Josephson voltage standard potentiometer. It can be used for high precision arbitrary resistance ratio measurements. For this purpose a 18 channel DAC based current source was developed to control all segments of binary divided 1-V Josephson voltage standard arrays. Additionally different types of current sources to generate the measurement current are built up to test the influence of current noise on the measurement uncertainly. First test measurements on two thermally controlled 12.9 kΩ resistors revealed resistance ratio measurement uncertainties in the 10^-9 range.