System and method for current measurement in the presence of high common mode voltages

摘要

A system and method for making accurate current measurements by determining the differential voltage drop across a resistor in series with the load in the presence of large common mode voltages. A compensating voltage equal in magnitude but 180 degrees out of phase with a common mode voltage is generated and applied to a network of resistors connected to a measurement amplifier, thereby significantly reducing the magnitude of the common mode voltage at the measurement amplifier's inputs. An error correction voltage is generated and applied to the output of the measurement amplifier to compensate for errors in the values of the resistor network.