AN IMPROVED CURRENT-COMPARATOR-BASED 1000-A TRANSCONDUCTANCE AMPLIFIER FOR THE IN-SITU CALIBRATION OF TRANSFORMER LOSS MEASURING SYSTEMS

A current-comparator technique, together with an error feed-forward co ntrol strategy, is applied to the design of a high-current transconduc tance amplifier to obtain a. highly stable and accurate output current . The transconductance amplifier features a current output range of 10 00 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 ou tput current has accuracies of better than +/-10 ppm (parts-per-millio n) in both magnitude and phase.