Article

Realization of the farad from the dc quantum Hall effect with digitally-assisted impedance bridges

Metrologia (Impact Factor: 2.04). 03/2010; 47(4). DOI: 10.1088/0026-1394/47/4/013
Source: arXiv

ABSTRACT

A new traceability chain for the derivation of the farad from dc quantum Hall effect has been implemented at INRIM. Main components of the chain are two new coaxial transformer bridges: a resistance ratio bridge, and a quadrature bridge, both operating at 1541 Hz. The bridges are energized and controlled with a polyphase direct-digital-synthesizer, which permits to achieve both main and auxiliary equilibria in an automated way; the bridges and do not include any variable inductive divider or variable impedance box. The relative uncertainty in the realization of the farad, at the level of 1000 pF, is estimated to be 64E-9. A first verification of the realization is given by a comparison with the maintained national capacitance standard, where an agreement between measurements within their relative combined uncertainty of 420E-9 is obtained. Comment: 15 pages, 11 figures, 3 tables

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Available from: Luca Callegaro, Mar 21, 2015
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    • "The coaxial circuit diagram of the bridge is shown in Fig. 4, and a photograph in Fig. 5. The electromagnetic current comparator and the polyphase synthesized generator employed in the implementation are described in detail in [13] [14]. The detector employed is a commercial Stanford Research mod. "
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