AccuBridge™ towards the development of a DC Current Comparator resistance ratio standard

Inherent ratio errors of 0.1 to 0.2 ppm in the Direct Current Comparator (DCC) have hindered its development as a standalone bridge. By improving the technologies described in the paper, the reduction of the inherent ratio error to <; 0.02 ppm can be achieved. Verification of the ratio accuracy can now be performed from a ratio of 0.07:1 to 14:1 with a resolution of 0.001 ppm. Automatic balancing facilitates the operation of the bridge for more accurate resistance measurements over the range of 0.1Ω to 100 kΩ.