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Balanced Magnetic Field

IP.com Disclosure Number: IPCOM000078573D
Original Publication Date: 1973-Feb-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 38K

Publishing Venue

IBM

Related People

O'Day, RL: AUTHOR

Abstract

A magnetic read head with two magnetoresistive (MR) elements shunt biased by a central biasing material, may be differentially sensed to eliminate common mode noise.

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Balanced Magnetic Field

A magnetic read head with two magnetoresistive (MR) elements shunt biased by a central biasing material, may be differentially sensed to eliminate common mode noise.

MR elements exhibit a linear change in resistance for given magnetic flux linkages during only a small range of operations. Therefore, it is desirable to provide a magnetic bias, which will center the operation range of the element at a point in the linear region. However, temperature sensitivity and other variables make it difficult to maintain this operating point.

A central bias strip, made of a material such as titanium that is electrically conductive, carries an MR element on each surface. The MR elements are isolated from direct electrical contact with the bias strip. Current flowing through the elements is shunted through the central bias strip, which generates the field necessary for biasing the MR elements. The elements are connected into a bridge circuit, and the output is monitored by a differential amplifier which rejects the temperature drift common mode. Thus, operating point drift with temperature change will be cancelled, by the differential summation of the output signals.

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