U.S. Philips Corporation

Martinus H Van Delden

Mark Thomas Johnson

Kars-Michiel Hubert Lenssen

Freddy Roozeboom

Marcellinus J Pelgrom

Gerjan F Van De Walle

A magnetic field sensor has a substrate on which a plurality of resistive elements form a double Wheatstone bridge circuit, at least one of the resistive elements in each bridge having a magneto-resistive characteristic. The two bridges are identical except in that, if a given magneto-resistive element in a given branch in one bridge has a positive output polarity, then the corresponding magneto-resistive element in the same branch in the other bridge will have a negative output polarity. By adding the output signals of the two Wheatstone bridges a zero-point offset of the sensor can be determined and eliminated. There is no need to employ the so-called flipping technique employed for that purpose in conventional sensors, which requires increased power consumption.

Magnetic field sensor with double wheatstone bridge having

Magnetic heads comprising at least one core portion of polycrystalline MnZn-ferroferrite material exhibit a very low so-called 'rubbing noise' level if the average grain size of the material ranges between 0.2 and 3.0 micrometers. The rubbing noise level of these heads is even lower than the electronic noise level if the average grain size of the material ranges between 0.5 and 2.0 micrometers. By virtue thereof, the heads can very suitably be used in the frequency range from 5 to 100 MHz.

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Eindhoven, Netherlands

Martinus H Van Delden