Measurement of the time constant of four-terminal resistor based on dissipation factor of capacitor

Abstract

Dissipation factor of the capacitor can be measured precisely by capacitance bridge. A kind of transfer circuit containing the auxiliary balancing circuit is used to compare the four-terminal resistor and the standard capacitor. Voltages of the two kinds of impedance are sampled synchronously by a two-channel digitizer. The phase difference of the voltages is computed by improved DFT algorithm. Based on the dissipation factor of the standard capacitor, time constant of the resistor can be computed. Experiments show the uncertainty of 8 ns with this method.