Progress in linking the Farad and the R/sub K/ value to the SI units at BNM-LCIE

A calculable capacitor and a quadrature bridge are used at the Bureau National de Metrologie-Laboratoire Central des Industries Electriques to link the unit of capacitance and the R/sub K/ value to the SI units. Re-evaluation of the frequency effect of the calculable capacitor and modifications to its movable guard-guiding system have improved the results of these two direct determinations. The measured value of the von Klitzing constant is: R/sub K/=R/sub K-90/(1+4.1/spl times/10/sup -8/), with 1/spl sigma/ uncertainty of 5.3 in 10/sup 8/.