DRIVE SYSTEM FOR MICROMACHINED MAGNETIC FIELD SENSORS
Described herein are systems, devices, and methods that provide a stable magnetometer. The magnetometer includes a drive element that facilitates flow of a drive current through a node and a sense element operable to detect a magnetic field operating on the drive current. To reduce offset in the detection of the magnetic field, a voltage detector, electrically coupled to the drive element through the node, determines a variation between a node voltage and a target voltage. The voltage detector facilitates suppression of the variation and thereby minimizes the offset in the sense element.
1 . A system, comprising:
a drive element that facilitates flow of a drive current through a node;
a sense element operable to detect a magnetic field operating on the drive current; and
a voltage detector electrically coupled to the drive element through the node, wherein the voltage detector determines a variation between a node voltage and a target voltage and facilitates suppression of the variation to minimize an offset in the sense element.
2 . The system of claim 1 , wherein the node is a coupling point for the drive element and the sense element.
3 . The system of claim 1 , wherein the node is located substantially at a midpoint of the drive element.
4 . The system of claim 1 , further comprising a feedback loop coupled to the voltage detector and the drive element that facilitates the suppression of the variation.
5 . The system of claim 4 , wherein the drive element is operable to facilitate differential flow of current.
6 . The system of claim 5 , wherein the feedback loop effectuates common-mode feedback to suppress the variation.
7 . The system of claim 1 , wherein a pulse width of the drive current is less than 50 percent of the drive period.
8 . The system of claim 1 further comprising:
a current detector electrically coupled to the drive element, wherein the current detector detects the drive current; and
a second loop filter electrically coupled to the current detector and the drive element, wherein the second loop filter is operable to adjust the drive current.
9 . The system of claim 8 , wherein the second loop filter suppresses variation in the drive current.
10 . A device, comprising:
a drive element that facilitates flow of a drive current with a drive pulse width of less than 50 percent of the drive period through a node;
a sense element operable to detect a magnetic field operating on the drive current; and
a drive circuit electrically coupled to the drive element, wherein the drive circuit provides the drive element with the drive current.
11 . The device of claim 10 , further comprising:
a voltage detector electrically coupled to the drive element through the node, wherein the detector detects a node voltage and determines a variation between the node voltage and a target voltage; and
a feedback loop electrically coupled to the drive element and the voltage detector, wherein the feedback loop suppresses the variation.
12 . The device of claim 11 , wherein the feedback loop comprises a loop filter that suppresses the variation.
13 . The device of claim 10 , wherein the node is a coupling point for the drive element and the sense element.
14 . The device of claim 10 , wherein the node is located substantially at a midpoint of the drive element.
15 . A method, comprising:
reducing a magnetic sensor offset, comprising:
detecting a voltage at a node coupling a drive element of a magnetic sensor and a sense element of the magnetic sensor;
determining a variation between the detected voltage and a reference voltage; and
reducing the variation in the detected voltage by using a feedback loop so that the detected voltage approximately matches the reference voltage; and
sensing a magnetic field acting on the drive element at the sense element.
16 . The method of claim 15 , further comprising driving the drive element with a drive current.
17 . The method of claim 16 , further comprising:
detecting an amplitude of the drive current;
determining a second variation between the detected amplitude and a reference amplitude; and
regulating the drive current to substantially eliminate the second variation.
18 . The method of claim 16 , wherein the driving further comprises driving the drive element with a drive current with a drive pulse width less than 50 percent of the drive period.
19 . The method of claim 16 , further comprising facilitating a differential flow of current through the drive element.
20 . The method of claim 19 , wherein the reducing further comprises reducing the variation in the detected voltage by using a feedback loop effectuating common-mode feedback.