H. Bachmair et al., REALIZATION AND MAINTENANCE OF THE UNIT OF CAPACITANCE WITH THE PTB CROSS CAPACITOR DURING THE LAST 10 YEARS, IEEE transactions on instrumentation and measurement, 44(2), 1995, pp. 440-442
A precise realization of the unit of capacitance is important for the
determination of both the Josephson and the von Klitzing constants. Th
e main design criteria of the PTB's cross capacitor, the maintenance o
f the unit of capacitance over the last 10 years, and a special capaci
tance-measuring bridge for tracing back the electrode capacitance in t
he absolute volt experiment to SI units are described in this paper.