Magnetic field sensor with automatic sensitivity adjustment
First Claim
1. A magnetic field sensor, comprising:
- a magnetic field sensing element supported by a substrate, the magnetic field sensing element for generating an output signal comprising a magnetic-field-responsive signal portion, wherein the magnetic-field-responsive signal portion has a sensitivity to a first magnetic field;
a feedback circuit, comprising;
a current conductor supported by the substrate and proximate to the magnetic field sensing element, the current conductor for generating a second magnetic field; and
a gain-calculation circuit configured to generate a gain-calculated signal and a gain-adjustment signal both responsive to the second magnetic field, wherein the gain-calculation circuit comprises a sample-and-hold circuit configured to sample and hold the gain-calculated signal in response to an enable signal to generate the gain-adjustment signal; and
a gain-adjustment circuit supported by the substrate and having a gain-adjustment node coupled to receive the gain-adjustment signal, wherein the gain-adjustment circuit is configured to adjust the sensitivity of the magnetic-field-responsive signal portion in response to the gain-adjustment signal.
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Accused Products
Abstract
Magnetic field sensors have a magnetic field sensing element and also a feedback circuit to provide a gain-adjustment signal to affect a sensitivity associated with the magnetic field sensing element. In some arrangements, the feedback circuit can include piezoresistors to sense a strain of a substrate over which the magnetic field sensor is disposed. With these arrangements, the feedback circuit can generate the gain-adjustment signal in accordance with the sensed strain. In other arrangements, the feedback circuit can generate pulsed magnetic fields proximate to the magnetic field sensing element in order to directly measure the sensitivity of the magnetic field sensing element. With these arrangements, the feedback circuit can generate the gain-adjustment signal in accordance with the sensed sensitivity.
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Citations
23 Claims
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1. A magnetic field sensor, comprising:
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a magnetic field sensing element supported by a substrate, the magnetic field sensing element for generating an output signal comprising a magnetic-field-responsive signal portion, wherein the magnetic-field-responsive signal portion has a sensitivity to a first magnetic field; a feedback circuit, comprising; a current conductor supported by the substrate and proximate to the magnetic field sensing element, the current conductor for generating a second magnetic field; and a gain-calculation circuit configured to generate a gain-calculated signal and a gain-adjustment signal both responsive to the second magnetic field, wherein the gain-calculation circuit comprises a sample-and-hold circuit configured to sample and hold the gain-calculated signal in response to an enable signal to generate the gain-adjustment signal; and a gain-adjustment circuit supported by the substrate and having a gain-adjustment node coupled to receive the gain-adjustment signal, wherein the gain-adjustment circuit is configured to adjust the sensitivity of the magnetic-field-responsive signal portion in response to the gain-adjustment signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A magnetic field sensor, comprising:
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a magnetic field sensing element supported by a substrate, the magnetic field sensing element for generating an output signal comprising a magnetic-field-responsive signal portion, wherein the magnetic-field-responsive signal portion has a sensitivity to a first magnetic field; a feedback circuit, comprising; a current conductor supported by the substrate and proximate to the magnetic field sensing element, the current conductor for generating a second magnetic field; a second magnetic field sensing element supported by the substrate, wherein the second magnetic field sensing element is responsive to the second magnetic field; and a gain-calculation circuit configured to generate a gain-adjustment signal responsive to the second magnetic field, wherein the second magnetic field sensing element generates an output signal related to the gain-adjustment signal; and a gain-adjustment circuit supported by the substrate and having a gain-adjustment node coupled to receive the gain-adjustment signal, wherein the gain-adjustment circuit is configured to adjust the sensitivity of the magnetic-field-responsive signal portion in response to the gain-adjustment signal.
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17. A magnetic field sensor, comprising:
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a magnetic field sensing element supported by a substrate, the magnetic field sensing element for generating an output signal comprising a magnetic-field-responsive signal portion, wherein the magnetic-field-responsive signal portion has a sensitivity to a first magnetic field; a feedback circuit, comprising; a current conductor supported by the substrate and proximate to the magnetic field sensing element, the current conductor for generating a second magnetic field; a first piezoresistor supported by the substrate, the first piezoresistor having a node at which a first piezoelectric output signal is generated, wherein the first piezoelectric output signal is responsive to a strain of the substrate in a first direction and also responsive to the second magnetic field; and a gain-calculation circuit configured to generate a gain-adjustment signal responsive to the second magnetic field, wherein the first piezoelectric output signal is related to the gain-adjustment signal; and a gain-adjustment circuit supported by the substrate and having a gain-adjustment node coupled to receive the gain-adjustment signal, wherein the gain-adjustment circuit is configured to adjust the sensitivity of the magnetic-field-responsive signal portion in response to the gain-adjustment signal. - View Dependent Claims (18, 19, 20, 21, 22, 23)
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Specification