부산대학교 도서관

The stability and nonlinearity of a commercial AH 2700A capacitance bridge were studied beyond its specified capabilities using the Thompson–Lampard calculable capacitor (TLCC) at LNE, Trappes, France. The TLCC allows for continuous variation of measured capacitance between 0.4 and 1.2 pF with a resolution of two parts in 107 and stability better than one part in 109 over two days. This study aimed to determine the root cause of the saw-tooth nonlinearity pattern observed in the AH 2700A capacitance bridge. This pattern becomes apparent when the internal calibration is no longer valid, indicating deviations in the bridge circuit. Additionally, the dependence of capacitance nonlinearity on various factors such as frequency and capacitance value is described. This work enables automatic calibration of the commercial bridge with an uncertainty of sub-ppm level and allows for quick evaluation of TLCC’s nonlinearity and monitoring of any changes over time through in situ measurements.