Electricity: measuring and testing – Magnetic – Magnetometers
Patent
1994-11-04
1996-10-01
O'Shea, Sandra L.
Electricity: measuring and testing
Magnetic
Magnetometers
360113, 338 32R, G01R 3302
Patent
active
055613683
ABSTRACT:
A magnetic field sensor uses four individual magnetoresistive spin valve elements electrically connected in a bridge circuit. The spin valve elements are lithographically formed on the same substrate with their free layers having their magnetization axes parallel to one another. An electrically conductive fixing layer is formed on the substrate but is insulated from the spin valve elements. The application of current through the fixing conductor during fabrication of the field sensor fixes the direction of magnetization of two of the pinned layers to be antiparallel to the direction of magnetization of the other two pinned layers. The bridge circuit output voltage is responsive to an external magnetic field in the plane of the sensor. By appropriate fixing of the direction of magnetization of the pinned layers during sensor fabrication, and appropriate connection to the input and output leads, the bridge circuit output voltage is a measure of either the magnetic field or field gradient. The fixing conductor, or a separate current strap formed on the substrate, can be used to pass an unknown current over the sensor, in which case the bridge circuit output voltage is a measure of the unknown current.
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Dovek Moris M.
Fontana, Jr. Robert E.
Speriosu Virgil S.
Spong Jaquelin K.
Berthold Thomas R.
International Business Machines - Corporation
O'Shea Sandra L.
Patidar Jay M.
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