Continuously calibrated magnetic field sensor
First Claim
1. Magnetic field sensor comprising a reference magnetic field generator, a magnetic field sensing cell including a magnetic field sensing element, and a signal processing circuit connected to an output of the magnetic field sensing cell and comprising one or more feedback lines for correcting error fluctuations in the transfer characteristic of the magnetic field sensor, the reference magnetic field generator adapted to generate a frequency modulated reference magnetic field, wherein the signal processing circuit further includes a modulator connected to the magnetic field sensing cell, the modulator modulating the output signal thereof at a frequency different from the modulation frequency of the reference magnetic field generator.
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Abstract
A magnetic field sensor comprises a reference magnetic field generator (8), a magnetic field sensing cell (6) including Hall effect sensing elements (12), and a signal processing circuit (4) connected to the output (11) of the magnetic field sensing cell and comprising one or more feedback lines (27, 28) for correcting error fluctuations in the transfer characteristic of the magnetic field sensor. The reference magnetic field generator is adapted to generate a frequency modulated reference magnetic field. The signal processing circuit further includes a modulator connected to the magnetic field sensing cell, adapted to modulate the output signal thereof at a frequency different from the modulation frequency of the reference magnetic field generator.
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Citations
21 Claims
- 1. Magnetic field sensor comprising a reference magnetic field generator, a magnetic field sensing cell including a magnetic field sensing element, and a signal processing circuit connected to an output of the magnetic field sensing cell and comprising one or more feedback lines for correcting error fluctuations in the transfer characteristic of the magnetic field sensor, the reference magnetic field generator adapted to generate a frequency modulated reference magnetic field, wherein the signal processing circuit further includes a modulator connected to the magnetic field sensing cell, the modulator modulating the output signal thereof at a frequency different from the modulation frequency of the reference magnetic field generator.
- 19. Method of measuring an external magnetic field, including the steps of superimposing a modulated reference magnetic field on the external magnetic field, modulating the output signal of a magnetic field sensing cell at a frequency different from the modulation frequency of the reference magnetic field, and adding or subtracting different phases of the modulated signal in order to separately extract a measurement signal corresponding to the external magnetic field and a reference signal corresponding to the reference magnetic field.
Specification