10x10 G/spl Omega/ Guarded Hamon Network for the Modified Wheatstone Bridge for High Value Resistors Calibration

At the National Institute of Metrological Research (INRIM), a Hamon guarded 10×100 MΩ network was developed to improve the traceability levels of dc resistance at 1 GΩ level. Utilizing and revisiting this project, a Hamon 10×10 GΩ network is developed to extend the capabilities of the Hamon scaling technique up to 100 GΩ. The novelty of the 10 × 10 GΩ network is its improved guard system, and the improvement for INRIM is the extension of the range of the Hamon scaling method up to 100 GΩ A description of this technique at INRIM, accurate construction details of the network and of its particular suitability for the modified Wheatstone bridge for high resistors calibration measurement method are given. The 1:100 transfer reliability test of the network gave satisfactory results. An uncertainty budget from 10 kΩ to 100 GΩ is worked out. Some measurement results on the network, both in parallel and in series configuration, are shown.