Precision computer-controlled decade capacitor

A precision computer-controlled decade capacitor switching capacitance values from 100 pF to 1 /spl mu/F in steps of 100 pF with an uncertainty of the order 10/sup -6/ is described. To minimize the temperature influence, special ceramic capacitors with temperature coefficients of 10/sup -6/ K/sup -1/ and low loss factor are used. Switching impedances are avoided by a four-terminal-pair definition of capacitors and quasi-coaxial connection. The capacitor can be used for automatic calibrations of capacitance bridges with a basic accuracy of 10/sup -4/ to 10/sup -5/.