Comparison among three impedance bridges for capacitance measurements at the nF range

This paper describes capacitance comparisons among three impedance bridges in operation at Inmetro in the nF range: the two- and four-terminal-pair coaxial bridges and a digital quadrature bridge. This comparison has 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 to one another in the 10
⁻⁷
level. The digital bridge is in agreement with the coaxial ones within parts in 10
⁶
.