Monolithic 4-20 mA isolating current replicator using GMR resistors

This circuit is an isolated current replicator that produces an output current that closely matches that present in an isolated input current loop. Typical uses of this circuit would be as an isolated receiver of 4-20 mA transducer data or in a traditional isolation amplifier. This device uses four magnetic field sensitive resistors in a bridge configuration in conjunction with two on-chip current loops and a conventional bipolar operational amplifier. The resistive sensors employ giant magnetoresistive ratio (GMR) material that displays a high magnetic sensitivity and is easily incorporated into a conventional integrated circuit process.