Chopped Hall effect sensor
First Claim
1. A Hall effect sensor comprising:
- a Hall element having an output at which is provided a Hall output signal that varies in response to a magnetic field, the Hall output signal comprising a magnetic signal component and an offset signal component;
a Hall plate modulation circuit having an input responsive to the Hall output signal and having an output at which is provided a modulation circuit output signal, wherein the Hall plate modulation circuit is operable to modulate the magnetic signal component or the offset signal component at a modulation frequency fCLK;
an amplifier having an input responsive to the Hall plate modulation circuit output signal and an output at which is provided an amplifier output signal; and
a filter having an input responsive to the amplifier output signal and an output at which is provided a sensor output signal, wherein the filter comprises an anti-aliasing filter and a discrete time selective filter tuned at the modulation frequency to remove the offset signal component, wherein the anti-aliasing filter provides a bandwidth limited signal for filtering by the selective filter, wherein the anti-aliasing filter removes frequency components above a predetermined frequency selected to prevent aliasing by the discrete time selective filter.
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Abstract
A chopped Hall effect sensor topology includes a switched Hall plate, an amplifier responsive to an output of the switched Hall plate and a filter stage responsive to the output of the amplifier and including an anti-aliasing filter and a selective filter that is tuned to the modulation frequency. The switched Hall plate includes a Hall element and a Hall plate modulation circuit that modulates the Hall offset signal component or the magnetic signal component. In embodiments in which the Hall offset signal component is modulated by the switched Hall plate, the amplifier, if chopped, includes an even number of additional modulation circuits. In embodiments in which the magnetic signal component is modulated by the switched Hall plate, the amplifier contains an odd number of modulation circuits. The described topology provides a low noise, fast response time Hall effect sensor.
119 Citations
25 Claims
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1. A Hall effect sensor comprising:
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a Hall element having an output at which is provided a Hall output signal that varies in response to a magnetic field, the Hall output signal comprising a magnetic signal component and an offset signal component; a Hall plate modulation circuit having an input responsive to the Hall output signal and having an output at which is provided a modulation circuit output signal, wherein the Hall plate modulation circuit is operable to modulate the magnetic signal component or the offset signal component at a modulation frequency fCLK; an amplifier having an input responsive to the Hall plate modulation circuit output signal and an output at which is provided an amplifier output signal; and a filter having an input responsive to the amplifier output signal and an output at which is provided a sensor output signal, wherein the filter comprises an anti-aliasing filter and a discrete time selective filter tuned at the modulation frequency to remove the offset signal component, wherein the anti-aliasing filter provides a bandwidth limited signal for filtering by the selective filter, wherein the anti-aliasing filter removes frequency components above a predetermined frequency selected to prevent aliasing by the discrete time selective filter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification