Hall effect isolation amplifier
First Claim
1. An isolation amplifier comprising:
- first magnetic field means for producing a magnetic field in response to an input signal;
Hall effect means for producing an induced voltage in response to said magnetic field; and
second magnetic field means for producing a compensating magnetic field approximately cancelling said magnetic field at said Hall effect means in response to said induced voltage.
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Accused Products
Abstract
An isolation amplifier circuit is described that utilizes a magnetic field in combination with a Hall effect device to isolate input signals and output signals. The input signal is applied to a conducting coil that produces a magnetic field in a Hall effect material through which current is flowing. Because of the Hall effect, terminals on the sides of the Hall effect material can provide a voltage difference. This voltage difference is amplified and applied to a second conducting coil. The second conducting coil is adapted to provide a magnetic field in the opposite direction from the magnetic field produced by the input signal. When the magnetic fields are identical, no difference in current flowing through the two terminals will be present. The output signal of the difference amplifier circuit will be a function of the input signal. According to a second embodiment, apparatus is included for cancelling ambient magnetic fields. A second isolation amplifier circuit is arranged to have a spatial orientation rotated 180° from a first isolation amplifier. With this configuration, ambient magnetic fields will have cancelling effects. The Hall effect device can be implemented in a PNP transistor with a split collector. The isolation amplifier can be fabricated with monolithic technology.
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Citations
21 Claims
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1. An isolation amplifier comprising:
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first magnetic field means for producing a magnetic field in response to an input signal; Hall effect means for producing an induced voltage in response to said magnetic field; and second magnetic field means for producing a compensating magnetic field approximately cancelling said magnetic field at said Hall effect means in response to said induced voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. The method of isolating an input signal from an output signal comprising the steps of:
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producing a magnetic field in a Hall effect device proportional to an input signal; utilizing an induced Hall effect signal to provide an output signal; and providing a compensating magnetic field in said Hall effect device proportional to said output signal. - View Dependent Claims (10, 11, 12)
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13. An isolation amplifier circuit comprising:
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a Hall effect material; current means for providing a current flowing through said Hall effect material, a first and a second terminal of said material generally being at the same potential in an absence of a magnetic field; magnetic field means for applying a magnetic field to said current means, said magnetic field means causing said first and said second terminal to have a different potential; and feedback means coupled to said first and said second terminal for applying a magnetic field to said Hall effect device cancelling said magnetic field means magnetic field, said feedback means for also providing an output signal determined by a magnitude of said cancelling magnetic field. - View Dependent Claims (14, 15, 16)
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17. An isolation amplifier comprising:
a first isolation circuit including; a first region of conducting material; a Hall effect material having a current flowing therethrough, said Hall effect material having two output terminals, wherein a signal applied to said region causes a magnetic field to be applied to said Hall effect material and a voltage difference to be applied between said output terminals; an amplifier having input terminals coupled to said Hall effect material output terminals; and a second region of conducting material coupled to an output terminal of amplifier, said second region of conducting material causing a magnetic field in said Hall effect material cancelling said first region magnetic field. - View Dependent Claims (18, 19, 20, 21)
Specification