Comparison of a 1 nF Capacitor with a 1 kΩ Resistor Using a Digital Impedance Bridge

This paper reports our effort to improve a digital impedance bridge. The limit of the bridge resolution and stability is less than 3 parts in 10
⁹
for the nominal 1:1 impedance comparison of two 100 pF capacitors. The Type A uncertainty for comparison of a 1 nF capacitor with a 1 kΩ resistor is about 1 part in 10
⁸
, presently limited by the stability of the resistor.