SUPPRESSION OF BARKHAUSEN NOISE IN MAGNETORESISTIVE SENSORS EMPLOYINGAC BIAS

A magnetic field rotating in the plane of a thin-film magnetoresistive sensor provides continuous saturation of the ferromagnetic material i f the magnitude of the field was sufficiently large. This mode of exci tation allows operation free of errors related to remanence and in the same time it helps in suppressing the Barkhausen noise. The experimen t demonstrates that the contribution of the magnetic noise in the sens or output is negligible when the period of the field rotation is less than 1 ms. This enables resolution of de and tow-frequency magnetic fi elds of the order of 10(-10) T/root Hz. This result can be improved by decreasing the sensor induced anisotropy and a resolution of 10(-11) - 10(-12) T/root Hz might be attainable.