Electricity: measuring and testing – Magnetic – Magnetometers
Reexamination Certificate
2007-06-15
2009-12-29
LeDynh, Bot L (Department: 2858)
Electricity: measuring and testing
Magnetic
Magnetometers
C324S207210
Reexamination Certificate
active
07639005
ABSTRACT:
A giant magnetoresistive sensor apparatus is described that provides improved multilayer quality, hysteresis, linearity and sensitivity. The multilayer structure includes NiFeCr as buffer and cap layers. The sensing resistor is designed in the form of a serpentine structure. To minimize the hysteresis and improve the linearity, the resistor end is tapered and elongated. In forming the sensor in a Wheatstone bridge configuration, two resistors are shielded by thick NiFe layers, while the two sensing resistors are not shielded and open to external signal fields. The shields can not only shield the influence of the external field on the shielded resistors but also serve as magnetic flux concentrators to magnify the external field on the unshielded resistors. The bridge output reflects the resistance change of the two unshielded sensing resistors.
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Baubock Gunther
O'Connell Barry T.
Qian Zhenghong
Advanced Microsensors, Inc.
Foley & Hoag LLP
LeDynh Bot L
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