Magnetic-field sensor with split-drain MOSFETS

摘要

A magnetic-field sensor has an array of split-drain transistors connected in parallel, each having a first, a second, and a third drain electrode, and a negative reference current generating transistor. A biasing circuit is utilized to bias the split-drain transistors in the saturated state, and to actuate the negative reference current generating transistor to generate a negative reference current. A first, a second, and a third current mirror are all controlled by a reference voltage. The second current mirror is coupled to the second drain electrode of each of the split-drain transistors to keep the reference voltage at a reference level. The first current mirror is coupled to the first drain electrode of each of the split-drain transistors to generate a first sensed current, and the third current mirror is coupled to the third drain electrode of each of the split-drain transistors to generate a second sensed current. A positive reference current generating transistor is controlled by the reference voltage to generate a positive reference current. The first and second sensed currents, and the negative and positive reference currents can be utilized to indicate the strength of the magnetic field.