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Amplifying the Hall Effect Signal

IP.com Disclosure Number: IPCOM000073759D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Collins, TW: AUTHOR

Abstract

This method combines two different effects of a push-pull type Hall element to multiply the Hall effect so as to increase the push-pull type Hall element's apparent sensitivity. Drawing A shows a push-pull type Hall element under the condition of zero applied field. Under this condition, the current splits evenly and no Hall voltage is generated across the contacts 1 and 2.

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Amplifying the Hall Effect Signal

This method combines two different effects of a push-pull type Hall element to multiply the Hall effect so as to increase the push-pull type Hall element's apparent sensitivity. Drawing A shows a push-pull type Hall element under the condition of zero applied field. Under this condition, the current splits evenly and no Hall voltage is generated across the contacts 1 and 2.

When a magnetic field is applied as shown in drawings B and C, two effects occur. The first effect is that a Hall voltage is generated between the Hall contacts 1 and 2. The polarity of this Hall voltage is determined by the polarity of the magnetic field applied. The second effect is that the current splitting becomes unbalanced, tending to increase the current in one lead and decreasing the current in the other. This current switching happens in conjunction with the generation of the Hall voltage and is caused by the apparent change in resistance in each direction due to the rotation of the equipotential lines caused by the Hall effect.

The multiplication of these two effects can be achieved by driving an active amplifying device with both the output Hall voltage and the Hall current, such that the Hall voltage and the Hall current aid each other in the active device.

Two such devices are shown. Fig. D shows an AC coupled bipolar circuit employing a push-pull type Hall effect element 5. Fig. E shows a DC coupled MOS FET n-channel depletion mode circuit incor...