Patent ID: 6025979
Filing Date: 2000-02-15
Classification: B82Y,G01R,G11B

Abstract:
A magnetoresistive sensor for sensing an external magnetic field, comprising:a magnetic bias field source generating an alternating magnetic bias field that alternates between a first direction and a second direction opposite to said first direction;a giant magnetoresistive sensing element, disposed within said alternating magnetic bias field, having a first ferromagnetic layer with magnetization pinned in said first direction, and a second ferromagnetic layer with alterable magnetization, the electrical resistance of the giant magnetoresistive sensing element being lower when said second ferromagnetic layer is magnetized in said first direction than when said second ferromagnetic layer is magnetized in said second direction; anda resistance detecting circuit coupled to said giant magnetoresistive sensing element, for detecting changes in electrical resistance in said giant magnetoresistive sensing element caused by said external magnetic field and said alternating magnetic bias field acting in combination;wherein said alternating magnetic bias field by itself magnetizes said second ferromagnetic layer in only one of said first direction and said second direction.