Magnetic field sensor and electronic circuit that pass amplifier current through a magnetoresistance element
First Claim
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1. An electronic circuit coupled to receive a power supply voltage, comprising:
- a first magnetoresistance element having first and second terminals, each one of the first and second terminals directly coupled to the magnetoresistance element;
a first transistor having a control node, a first current passing node, and a second current passing node;
a first fixed voltage generating source having first and second nodes between which a first fixed voltage is generated, wherein the first fixed voltage does not change in response to a changing magnetic field, wherein the first terminal of the first magnetoresistance element is coupled to the first current passing node of the first transistor, wherein the control node of the first transistor receives the first fixed voltage, and the second node of the first fixed voltage generating source is coupled to the second terminal of the first magnetoresistance element, wherein the electronic circuit is operable to generate a first current signal at the second current passing node of the first transistor related to a resistance value of the first magnetoresistance element;
a first fixed resistor having a first fixed resistance that does not change in response to the changing magnetic field and having first and second terminals;
a second transistor having a control node, a first current passing node, and a second current passing node;
a second fixed voltage generating source having first and second nodes between which a second fixed voltage is generated, wherein the second fixed voltage does not change in response to the changing magnetic field; and
a first load coupled to the second current passing node of the first transistor, wherein the second current passing node of the first transistor is coupled to the second current passing node of the second transistor, wherein the first terminal of the first fixed resistor is coupled to the first current passing node of the second transistor, wherein the control node of the second transistor receives the second fixed voltage, and the second node of the second fixed voltage generating source is coupled to the second terminal of the first fixed resistor, wherein the electronic circuit is operable to generate a second current signal at the second current passing node of the second transistor related to a resistance value of the first fixed resistor, wherein a current passing through the first load is equal to a difference between the first current signal and the second current signal.
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Abstract
Electronic circuits used in magnetic field sensors use transistors for passing a current through the transistors and also through a magnetoresistance element.
336 Citations
22 Claims
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1. An electronic circuit coupled to receive a power supply voltage, comprising:
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a first magnetoresistance element having first and second terminals, each one of the first and second terminals directly coupled to the magnetoresistance element; a first transistor having a control node, a first current passing node, and a second current passing node; a first fixed voltage generating source having first and second nodes between which a first fixed voltage is generated, wherein the first fixed voltage does not change in response to a changing magnetic field, wherein the first terminal of the first magnetoresistance element is coupled to the first current passing node of the first transistor, wherein the control node of the first transistor receives the first fixed voltage, and the second node of the first fixed voltage generating source is coupled to the second terminal of the first magnetoresistance element, wherein the electronic circuit is operable to generate a first current signal at the second current passing node of the first transistor related to a resistance value of the first magnetoresistance element; a first fixed resistor having a first fixed resistance that does not change in response to the changing magnetic field and having first and second terminals; a second transistor having a control node, a first current passing node, and a second current passing node; a second fixed voltage generating source having first and second nodes between which a second fixed voltage is generated, wherein the second fixed voltage does not change in response to the changing magnetic field; and a first load coupled to the second current passing node of the first transistor, wherein the second current passing node of the first transistor is coupled to the second current passing node of the second transistor, wherein the first terminal of the first fixed resistor is coupled to the first current passing node of the second transistor, wherein the control node of the second transistor receives the second fixed voltage, and the second node of the second fixed voltage generating source is coupled to the second terminal of the first fixed resistor, wherein the electronic circuit is operable to generate a second current signal at the second current passing node of the second transistor related to a resistance value of the first fixed resistor, wherein a current passing through the first load is equal to a difference between the first current signal and the second current signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An electronic circuit coupled to receive a power supply voltage, comprising:
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a first magnetoresistance element having first and second terminals, each one of the first and second terminals directly coupled to the magnetoresistance element; a first transistor having a control node, a first current passing node, and a second current passing node; a first fixed voltage generating source having first and second nodes between which a first fixed voltage is generated, wherein the first fixed voltage does not change in response to a changing magnetic field, wherein the first terminal of the first magnetoresistance element is coupled to the first current passing node of the first transistor, wherein the control node of the first transistor receives the first fixed voltage, and the second node of the first fixed voltage generating source is coupled to the second terminal of the first magnetoresistance element, wherein the electronic circuit is operable to generate a first current signal at the second current passing node of the first transistor related to a resistance value of the first magnetoresistance element; a second magnetoresistance element having first and second terminals; a second transistor having a control node, a first current passing node, and a second current passing node; a second fixed voltage generating source having first and second nodes between which a second fixed voltage is generated, wherein the second fixed voltage does not change in response to the changing magnetic field; and a first load coupled to the second current passing node of the first transistor, wherein the second current passing node of the first transistor is coupled to the second current passing node of the second transistor, wherein the first terminal of the second magnetoresistance element is coupled to the first current passing node of the second transistor, wherein the control node of the second transistor receives the second fixed voltage, and the second node of the second fixed voltage generating source is coupled to the second terminal of the second magnetoresistance element, wherein the electronic circuit is operable to generate a second current signal at the second current passing node of the second transistor related to a resistance value of the second magnetoresistance element, wherein a current passing through the first load is equal to a difference between the first current signal and the second current signal, wherein the second terminals of the first and second magnetoresistance elements are not coupled together. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification