Magnetic field sensor configured to measure a magnetic field in a closed loop manner
First Claim
1. A magnetic field sensor for sensing an external magnetic field, the sensor comprising:
- at least one magnetic field sensing element for measuring a magnetic field produced by a first magnetic field generating source;
a current generator configured to receive one or more drive current signals at an input thereof and to generate a drive current signal having a periodic waveform and an amplitude offset at an output thereof;
a second magnetic field generating source configured to receive the drive current signal at an input thereof and in response thereto, provide a magnetic field to the at least one magnetic field sensing element;
a comparator configured to receive a reference voltage as a first input and an output signal from the at least one magnetic field sensing element as a second input, and in response thereto to generate a comparator output signal having a duty cycle; and
a compensation circuit configured to receive the comparator output signal having a duty cycle at an input thereof and to generate an offset signal for correcting the duty cycle to a predetermined duty cycle as an output wherein a characteristic of the offset signal is that it is proportional to a magnitude of the external magnetic field experienced by the magnetic field sensing element when the duty cycle of the comparator output signal is substantially the same as the predetermined duty cycle.
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Accused Products
Abstract
A magnetic field sensor for sensing an external magnetic field includes at least one magnetic field sensing element for measuring a magnetic field produced by a first magnetic field generating source and a current generator configured to receive one or more drive current signals at an input thereof and to generate a drive current signal having a periodic waveform and an amplitude offset at an output thereof. Also included is a second magnetic field generating source configured to receive the drive current signal at an input thereof and in response thereto, provide a magnetic field to the at least one magnetic field sensing element. Additionally included is a comparator configured to receive a reference voltage as a first input and an output signal from the at least one magnetic field sensing element as a second input, and in response thereto to generate a comparator output signal having a duty cycle. Further included is a compensation circuit configured to receive the comparator output signal having a duty cycle at an input thereof and to generate an offset signal for correcting the duty cycle to a predetermined duty cycle as an output. A corresponding method is also provided.
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Citations
33 Claims
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1. A magnetic field sensor for sensing an external magnetic field, the sensor comprising:
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at least one magnetic field sensing element for measuring a magnetic field produced by a first magnetic field generating source; a current generator configured to receive one or more drive current signals at an input thereof and to generate a drive current signal having a periodic waveform and an amplitude offset at an output thereof; a second magnetic field generating source configured to receive the drive current signal at an input thereof and in response thereto, provide a magnetic field to the at least one magnetic field sensing element; a comparator configured to receive a reference voltage as a first input and an output signal from the at least one magnetic field sensing element as a second input, and in response thereto to generate a comparator output signal having a duty cycle; and a compensation circuit configured to receive the comparator output signal having a duty cycle at an input thereof and to generate an offset signal for correcting the duty cycle to a predetermined duty cycle as an output wherein a characteristic of the offset signal is that it is proportional to a magnitude of the external magnetic field experienced by the magnetic field sensing element when the duty cycle of the comparator output signal is substantially the same as the predetermined duty cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 29, 31, 32, 33)
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18. A method of sensing an external magnetic field with a magnetic field sensor having hysteresis, the method comprising:
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generating a drive current signal having a periodic waveform and an amplitude offset at an output thereof; generating a magnetic field from said drive current signal and applying said magnetic field to a magnetic field sensing element; comparing an output of the magnetic field sensing element to a reference signal to generate a comparison output signal having a duty cycle characteristic; and generating an offset signal for correcting the duty cycle from the comparison output signal to a predetermined duty cycle wherein a characteristic of the offset signal is that it is proportional to the external magnetic field experienced by the magnetic field sensing element when the duty cycle of the comparison output signal is substantially the same as the predetermined duty cycle. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30)
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Specification