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The MagnetoResistive (MR) Effect
Magneto resistive sensor
In thin films of permalloy (FE-Ni) material, the electrical
resistance changes when an external magnetic field is applied in
the plane of the film. The change is due to the rotation of the film
magnetization. The variation of the resistance due an external
field is called the anisotropic magnetoresistive (AMR) effect.
Quelle : Prof. Dr. -Ing. J. M. Pacas, Universität Siegen
Current Measurement
The operating principle of by MRSensors
current sensors is based on a differential
field measurement with compensation.
The primary current is fed through a
conductor, creating a field gradient Hprim
between the two sides of the conductor.
The thin film magnetoresistive resistors
are placed on a silicon chip and are
connected in a Wheatstone bridge. The
chip is mounted together with the
analogue interface electronics on a single
in-line hybrid circuit. In order to obtain a
high linearity (0.1%) and a low
temperature sensitivity, a current I S is fed
back to the sensor chip through a
compensation conductor located above
the magnetoresistive resistors. The
resulting field Hcomp exactly
compensates Hprim, so that the sensor
always works around a single point. At
the output of the sensors, the
compensation current flows.