A wide-band active current transformer and shunt

An active current transformer and shunt with high accuracy and wide frequency range is described. The transformer, which uses two three-stage core transformers with two two-stage feedback amplifiers, can be used in the audio frequency band. It has a wide range of current ratio (0.01-1) and can dissipate 10 W in the external burden. If the external burden of the transformer is an AC standard resistor, it becomes an AC current to voltage transducer that can be used in many electrical measurements. The relative uncertainty (3σ) in the current ratio of the new transformer is between (1+j1) p.p.m. to (8+j8) p.p.m. over the frequency range from 40 Hz to 10 kHz