Magnetic field sensor with shared path amplifier and analog-to-digital-converter
First Claim
Patent Images
1. A magnetic field sensor comprising:
- at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field and to generate a reference magnetic field signal responsive to a reference magnetic field;
a signal path comprising an amplifier and an analog-to-digital converter for processing the measured magnetic field signal during a first time period to generate a sensor output signal indicative of the external magnetic field, and for processing the reference magnetic field signal during a second time period, the analog-to-digital converter comprising at least one integrator circuit having a first capacitor configured to process the measured magnetic field signal and a second capacitor configured to process the reference magnetic field signal, wherein the analog-to-digital converter is responsive to the measured magnetic field signal to generate a digital measured magnetic field signal and responsive to the reference magnetic field signal to generate a digital reference magnetic field signal;
a controller configured to switch the first capacitor with the second capacitor to enable the first capacitor to process the reference magnetic field signal; and
a comparator circuit to compare the reference magnetic field signal to a threshold value during the second time period to determine whether a fault is present;
wherein the first time period and the second time period are non-overlapping time periods.
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Abstract
Methods and apparatus for processing a signal comprise at least one circuit configured to generate a measured signal during a measured time period and a reference signal during a reference time period. Also included is at least one dual- or multi-path analog-to-digital converter comprising at least a first processing circuit configured to process the measured signal, at least a second processing circuit configured to process the reference signal, and a third processing circuit configured to process both the measured signal and the reference signal.
24 Citations
18 Claims
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1. A magnetic field sensor comprising:
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at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field and to generate a reference magnetic field signal responsive to a reference magnetic field; a signal path comprising an amplifier and an analog-to-digital converter for processing the measured magnetic field signal during a first time period to generate a sensor output signal indicative of the external magnetic field, and for processing the reference magnetic field signal during a second time period, the analog-to-digital converter comprising at least one integrator circuit having a first capacitor configured to process the measured magnetic field signal and a second capacitor configured to process the reference magnetic field signal, wherein the analog-to-digital converter is responsive to the measured magnetic field signal to generate a digital measured magnetic field signal and responsive to the reference magnetic field signal to generate a digital reference magnetic field signal; a controller configured to switch the first capacitor with the second capacitor to enable the first capacitor to process the reference magnetic field signal; and a comparator circuit to compare the reference magnetic field signal to a threshold value during the second time period to determine whether a fault is present; wherein the first time period and the second time period are non-overlapping time periods. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A magnetic field sensor comprising:
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at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field and to generate a reference magnetic field signal responsive to a reference magnetic field; a signal path comprising; a shared portion for processing the measured magnetic field signal during a first time period to generate a sensor output signal indicative of the external magnetic field, and for processing the reference magnetic field signal during a second time period, wherein the first and second time periods are non-overlapping time periods; a dedicated portion for processing the measured magnetic field signal during the first time period; and at least one integrator circuit having a first capacitor configured to process the measured magnetic field signal and a second capacitor configured to process the reference magnetic field signal; and a comparator circuit to compare the reference magnetic field signal to a threshold value during the second time period to determine whether a fault is present; and a controller configured to switch the first capacitor with the second capacitor to enable the dedicated portion of the signal path to process the reference magnetic field signal. - View Dependent Claims (10, 11, 12)
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13. A magnetic field sensor comprising:
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at least one magnetic field sensing element configured to generate a measured magnetic field signal responsive to an external magnetic field and to generate a reference magnetic field signal responsive to a reference magnetic field; a signal path for processing the measured magnetic field signal during a first time period to generate a sensor output signal indicative of the external magnetic field and for processing the reference magnetic field signal during a second time period, the signal path comprising at least one integrator circuit having a first capacitor configured to process the measured magnetic field signal and a second capacitor configured to process the reference magnetic field signal, wherein the first time period and the second time period are non-overlapping time periods; a controller configured to switch the first capacitor with the second capacitor to enable the second capacitor of the integrator circuit to process the reference magnetic field signal; a comparator circuit to compare the reference magnetic field signal to a threshold value during the second time period to determine whether a fault is present; and a diagnostic trim circuit configured to adjust a gain of the reference magnetic field signal, an offset of the reference magnetic field signal, or both. - View Dependent Claims (14, 15, 16, 17)
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18. A magnetic field sensor comprising:
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means for generating a measured magnetic field signal responsive to an external magnetic field; means for generating a reference magnetic field signal responsive to a reference magnetic field; a signal path comprising; means for processing the measured magnetic field signal during a first time period to generate a sensor output signal indicative of the external magnetic field; means for processing the reference magnetic field signal during a second time period; and means for converting the measured magnetic field signal and the reference magnetic field signal to digital signals, the means for converting comprising at least one integrator circuit having a first capacitor configured to process the measured magnetic field signal and a second capacitor configured to process the reference magnetic field signal; and means for selectively coupling the first capacitor to the signal path during the first time period and coupling the second capacitor to the signal path during the second time period; and means for detecting a fault and generating a signal indicative of whether a fault is present; wherein the first time period and the second time period are non-overlapping time periods.
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Specification