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

TL;DR

This paper presents a new traceability chain for realizing the farad from the dc quantum Hall effect using digitally-assisted impedance bridges, achieving high accuracy and automation.

Contribution

It introduces a novel automated impedance bridge system that eliminates variable components, enhancing precision in realizing the farad from quantum Hall standards.

Findings

Achieved a relative uncertainty of 64E-9 in farad realization.

Demonstrated agreement within 420E-9 with national capacitance standards.

Implemented fully automated bridges using digital synthesis.

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.