Coaxial and Digital Impedance Bridges for Capacitance Measurements at the nF Range

摘要

This paper describes three impedance bridges in operation at INMETRO: the two- and four-terminal-pair coaxial bridges and a digital quadrature bridge, including several comparisons among them in the nanofarad capacitance range. These comparisons have the objective to verify the performance and reliability of the coaxial bridges between themselves and to infer on the capabilities of a digital one, recently put in operation. The results obtained indicate that the more accurate coaxial systems are compatible with one another in the 10^{-7} level. The digital bridge is in agreement with the coaxial ones within a few parts in 10^{6} or even less in some cases.