An improved current-comparator-based 1000-A transconductanceamplifier for the in-situ calibration of transformer loss measuringsystems

A current comparator technique and an error feedforward control strategy are applied to the design of a high current transconductance amplifier to obtain a highly stable and accurate output current. The transconductance amplifier features a current output range of 1000 A with a compliance voltage of 3 V. It has the ability to provide a highly accurate current to a circuit that is operated at high voltage. This high-current transconductance amplifier is used in a system for the in-situ calibration of transformer loss measuring systems. The output current has accuracies of better than ±10 ppm (parts-per-million) in both magnitude and phase