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 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;
a second piezoresistor supported by the substrate, each one of the first and second piezoresistors having a respective primary response axis, wherein the first and second piezoresistors are disposed in a relative orientation so that their respective primary response axes are generally perpendicular, the second piezoresistor having a node at which a second piezoelectric output signal is generated, wherein the second piezoelectric output signal is responsive to a strain of the substrate in a second direction generally perpendicular to the first direction; and
a combining circuit having first and second input nodes coupled to receive signals related to the first and second piezoelectric output signals and having an output node at which a gain-adjustment signal is generated; 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
10 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 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; a second piezoresistor supported by the substrate, each one of the first and second piezoresistors having a respective primary response axis, wherein the first and second piezoresistors are disposed in a relative orientation so that their respective primary response axes are generally perpendicular, the second piezoresistor having a node at which a second piezoelectric output signal is generated, wherein the second piezoelectric output signal is responsive to a strain of the substrate in a second direction generally perpendicular to the first direction; and a combining circuit having first and second input nodes coupled to receive signals related to the first and second piezoelectric output signals and having an output node at which a gain-adjustment signal is generated; 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)
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Specification