AMPLIFICATION OF SIGNALS PRODUCED BY A CURRENT BIASED MAGNETORESISTIVE SENSOR

摘要

AMPLIFICATION OF SIGNALS PRODUCED BY A CURRENT BIASED MAGNETORESISTIVE SENSOR A transimpedance amplifier for biasing and amplifying the signals produced by a magnetoresistive element is provided. Electrically, the resistance of the element is disposed as degenerative feedback in the emitter circuit of a differential pair comprising the input stage of the amplifier. Bias current for the element is supplied by the same current source that supplies current to the differential pair. DC feedback to the input stage balances current flow in both paths of the differential input stage to correct for DC offset arising in the output from variations transistor characteristics and the steady-state value of the magnetoresistive element. The amplified signal, representing .DELTA.Rh/Rh, is sensed as a current through the magnetoresistive element, where .DELTA.Rh is the change in steady-state resistance, Rh, of the element.