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Two Drain FET Magnetic Field Sensor

IP.com Disclosure Number: IPCOM000074510D
Original Publication Date: 1971-May-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Arnett, PC: AUTHOR [+3]

Abstract

A two-drain field-effect transistor device perpendicular to a magnetic field will measure the strength and direction of the applied magnetic field.

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Two Drain FET Magnetic Field Sensor

A two-drain field-effect transistor device perpendicular to a magnetic field will measure the strength and direction of the applied magnetic field.

The drawing illustrates a field-effect transistor 10 created in a semiconductor body 11 comprising a source region 12, an elongated gate 13, a first drain region 14 and a second drain region 15 which will act as a sensitive magnetic field sensor for magnetic memories. When the device is positioned perpendicular to the magnetic field of a magnetic bubble or cylindrical domain, and operated, charge carriers flowing from the source 12 under the gate 13 will be deflected by the magnetic field arising out of the domain causing one drain to receive more current than the other drain. The differential current output of the two drains provides the measurement of magnetic field strength, while the direction on the magnetic field determines deflection in the path of the charge carriers. Therefore, the polarity of the differential output can also be used to determine the direction of the magnetic field as well.

This device is more sensitive than bipolar devices because current transport in the channel region under gate 13 is due to the drift of carriers, thus recombination does not occur in the channel regions. Therefore, a long channel length can be used with a resultant increase in interaction between the magnetic field and the device. Still further, because the main field of the magnetic dev...