Development of high accuracy standard capacitance box

This paper describes the dielectric material and the structure of the standard capacitance box (decade capacitor) developed by NIM with the capacitance range of 1pF to 0.1μF and the accuracy of 50ppm at 1 kHz. High stability and high accuracy of the standard capacitance box mainly derives from a choice of dielectric materials that are fused-silica and nano-ceramic, and each capacitor in the box contained a constant temperature control system. Special decade switch with the three-terminal full shield structure can eliminate the capacitance variance caused by the stray capacitance so that higher accuracy and lower zero capacitance can be achieved.