Calibration methods of a CC and BCG for a high-accuracy AC current ratio standard up to 4 kHz

This paper describes calibration methods of current comparators (CCs) and balancing current generators (BCGs) accompanied with them, for establishing a high-accuracy ac current ratio standard up to 4 kHz. The CC calibration is explained mathematically according to the self-calibration procedure that NMIJ has been exploiting. The BCG calibration is based on measurement of the conversion ratio. The technique with a CC and CT is unique in terms of the fact that the uncertainty can be ignored against the CT calibration.