Traceability Chain Establishment at KRISS from DC QHR to Farad Using AC-DC Calculable Resistor Standard and Digitally Assisted Coaxial Bridges

A national traceability chain from dc quantum Hall resistance (QHR) to capacitance has been established at KRISS using various impedance standards and ac coaxial bridges. Two bridges developed by INRiM, were employed: a quadrature bridge, calibrating 1000 pF capacitors versus 103 kΩ ac resistors and a ratio bridge, linking the ac resistor values to an ac-dc calculable resistor calibrated in terms of the dc QHR. The capacitance value obtained with the new traceability chain showed an agreement (a few parts in ${10}^{7}$ ) in a comparison with the scale maintained at National Institute for Standards and Technology (NIST, USA).