Patent ID: 7259556

Claim:
A magnetic field sensor for the measurement of at least one component of a magnetic field, comprising a ring-shaped ferromagnetic core attached to a semi-conductor chip that spans a plane with the at least one component of the magnetic field to be measured and that serves as magnetic field concentrator, whereby the ferromagnetic core is magnetized with a predetermined magnetization, a read-out sensor, whereby the read-out sensor comprises at least one sensor that is integrated into the semiconductor chip and arranged in the vicinity of an outer edge of the ferromagnetic core and that measures the at least one component of the magnetic field, an excitation coil and a first electronic circuit for the temporary application of a current to the excitation coil in order to restore the predetermined magnetization in the ferromagnetic core, wherein said predetermined magnetization produces no signal in the read-out sensor, and a second electronic circuit for the operation of the first electronic circuit, the read-out sensor and for processing a signal delivered by the read-out sensor.