The IEN CCC bridge to scale the quantized Hall resistance to 1-/spl Omega/ standards

A resistance bridge based on a cryogenic current comparator has been built at the Istituto Elettrotecnico Nazionale "G. Ferraris" (IEN). The use of this bridge simplifies the scaling down from the quantized Hall resistance to decadic standard resistors, at the same time reducing the measurement uncertainty. The bridge is described and the result of a comparison at the level of 100 /spl Omega/, with the traditional scaling method used at IEN is reported. The two methods agree well within their uncertainties, for which detailed uncertainty budgets are given.