High dynamic range digital fluxgate magnetometer
First Claim
1. Sensing apparatus comprising:
- a sensor comprising a feedback input, and a sense output that outputs an error signal indicative of the difference between a signal sensed by the sensor and a feedback signal input to the feedback input;
a comparator coupled to the sense output of the sensor;
a register coupled to the comparator that outputs a logical 1 or a logical 0 in accordance with the output of the comparator;
a digital filter coupled to the signal output of the register, for producing a digital output of the sensing apparatus;
a digital clock having a clock signal output coupled to clock inputs of the register and the digital filter; and
a high resolution digital to analog converter and analog low pass filter coupled between the register and the feedback input of the sensor for supplying the feedback signal thereto.
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Accused Products
Abstract
An improved digital fluxgate magnetometer that uses digital logic and a high resolution digital to analog converter to digitize a magnetic signal for use by signal processing algorithms. The magnetometer includes an oscillator that outputs an oscillator signal and a magnetic fluxgate sensor having a drive coil coupled to the oscillator, a feedback coil, and a sense coil. An analog multiplier is coupled to the sense coil and the oscillator and outputs a signal to an analog low pass filter. A comparator is coupled to the analog multiplier, and a register is coupled to the comparator and outputs a logical 1 or a logical 0 in accordance with the output of the comparator. A digital filter receives the output of the register and produces a digital output of the digital fluxgate magnetometer. A high resolution digital to analog converter is coupled between the register and the feedback coil of the magnetic fluxgate sensor in a feedback loop of the sensor. The digital to analog converter produces a very high resolution digitized output (typically >22 bits) that is necessary to adequately represent the dynamic range of the sensor.
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Citations
7 Claims
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1. Sensing apparatus comprising:
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a sensor comprising a feedback input, and a sense output that outputs an error signal indicative of the difference between a signal sensed by the sensor and a feedback signal input to the feedback input; a comparator coupled to the sense output of the sensor; a register coupled to the comparator that outputs a logical 1 or a logical 0 in accordance with the output of the comparator; a digital filter coupled to the signal output of the register, for producing a digital output of the sensing apparatus; a digital clock having a clock signal output coupled to clock inputs of the register and the digital filter; and a high resolution digital to analog converter and analog low pass filter coupled between the register and the feedback input of the sensor for supplying the feedback signal thereto. - View Dependent Claims (2, 3)
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4. A digital fluxgate magnetometer comprising:
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an oscillator that outputs an oscillator signal; a magnetic fluxgate sensor comprising core material, a drive coil, a feedback coil, and a sense coil, and wherein the oscillator is coupled to the drive coil; an analog multiplier having inputs coupled to the sense coil and the oscillator; an analog low pass filter coupled to an output of the analog multiplier; a comparator having a first input coupled to the low pass filter and having a second input coupled to ground; a register coupled to the comparator that outputs a logical 1 or a logical 0 in accordance with the output of the comparator; a digital filter coupled to receive the signal output of the register for producing a digital output of the digital fluxgate magnetometer; a high speed digital clock having a clock signal output coupled to clock inputs of the register and the digital filter; and a high resolution digital to analog converter coupled between the register and the feedback coil of the magnetic fluxgate sensor. - View Dependent Claims (5)
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6. An analog to digital converter comprising:
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a differential amplifier having a first input for receiving an analog input signal that is to be digitized; a comparator coupled to the differential amplifier; a register coupled to the comparator that outputs a logical 1 or a logical 0 in accordance with the output of the comparator; a high resolution digital to analog converter coupled between the register and a second input of the differential amplifier for supplying a feedback signal thereto; a digital filter coupled to the signal output of the register, for producing a digital output signal corresponding to the analog input signal; and a digital clock having a clock signal output coupled to clock inputs of the register and the digital filter. - View Dependent Claims (7)
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Specification