Patent attributes
Magnetic-field sensors use magnetic closed-loops with magnetic-field sensing elements, e.g., magnetoresistance (MR) elements, and diagnostic circuitry operating in a separate frequency band than that used for magnetic field sensing. The MR elements can be used in a first stage of a high gain amplifier which provides a feedback signal to a feedback coil in a feedback configuration to provide a magnetic feedback field. The magnetic feedback field attenuates the sensed magnetic field so that the MR elements operate in a linear range. Magnetic stray field effects and any limited linearity of magnetic-field sensing elements can be masked by the loop gain of the closed loop. For a magnetic closed-loop, a negative feedback configuration can be used or a positive feedback configuration can be used with a loop-gain of less than one. The diagnostic signal traverses the closed-loop and provides information regarding correct or incorrect functioning of the loop components.
