Calibration of electronic capacitance and dissipation factor bridges

A new calibration procedure for electronic capacitance and dissipation factor bridges is presented. These bridges measure the ratio of their input currents. For the calibration, two sinusoidal alternating currents are synthesized with the aid of a digital, programmable two-channel AC voltage source and two AC resistors. The complex ratio of these synthesized input currents is calculated from an AC voltage ratio determined by a sampling method, together with the impedance ratio of the AC resistors. At currents of a few mA, their complex ratio in the frequency range up to 100 Hz can be measured with uncertainties (k=2) of approximately 1×10^-6 and 1 μrad, respectively.