Browse Prior Art Database

Hall Effect Device Having Improved Signal to Noise Ratio

IP.com Disclosure Number: IPCOM000076479D
Original Publication Date: 1972-Mar-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Strnad, RJ: AUTHOR

Abstract

A Hall effect device having a plurality of output, has improved signal-to-noise ratio performance when the length-to-width of the device is greater than three, and the length and width are much greater than the misalignment factor.

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Hall Effect Device Having Improved Signal to Noise Ratio

A Hall effect device having a plurality of output, has improved signal-to-noise ratio performance when the length-to-width of the device is greater than three, and the length and width are much greater than the misalignment factor.

Assuming a constant thickness and a uniform charge velocity, a misalignment voltage at terminals 1 and 2 of the Hall device shown is given by: V1 = V2 = VIN(1/2 + or - r over 1) Where r = misalignment factor in mils. 1 = device length in mils.

A 4 mil wide and long Hall device, having an input voltage at 5 volts, can be shown to have a misalignment voltage of about + or - 125 mils volts for a Hall signal of VH proportional to 23 MV/5v KG. The signal-to-noise ratio for such a Hall device is 23/125 or about 0.18. A Hall device having a length 12 mils and a width 4 mils can be shown to have a misalignment voltage of + 30 mils volts and a signal-to-noise ratio of 0.36.

When the Hall device has a plurality of outputs as shown, it is highly improbable that all outputs will be misaligned in undesired directions. Such a circuit should have compensation for misalignment caused by imperfect masks in fabricating the device. High gain can be achieved particularly when outputs A, B and C move in a positive direction and outputs D, E and F move in a negative direction. If each transistor has a gain of 10, the total gain for R1 = R2 = 10K and for an I(0) = 200 microamps is greater than 10/3/. T...