Integrated fluxgate magnetic gradient sensor

Patent metadata

Field	Value
Publication number	US-2016349334-A1
Application number	US-201615162776-A
Country	US
Kind code	A1
Filing date	May 24, 2016
Priority date	May 27, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

An integrated fluxgate magnetic gradient sensor includes a common mode sensitive fluxgate magnetometer and a differential mode sensitive fluxgate magnetometer. The common mode sensitive fluxgate magnetometer includes a first core adjacent to a second core. The first and second cores are wrapped by a first excitation wire coil configured to receive an excitation current that affects a differential mode magnetic field. The differential mode sensitive fluxgate magnetometer includes a third core adjacent to the first core and a fourth core adjacent to the second core. The third and fourth cores are wrapped by a second excitation wire coil configured to receive an excitation current that affects a common mode magnetic field.

First claim

1 . An integrated fluxgate magnetic gradient sensor, comprising:
a common mode sensitive fluxgate magnetometer including a first core adjacent to a second core, the first and second cores wrapped by a first excitation wire coil configured to receive an excitation current that affects a differential mode magnetic field; and a differential mode sensitive fluxgate magnetometer including a third core adjacent to the first core and a fourth core adjacent to the second core, the third and fourth cores wrapped by a second excitation wire coil configured to receive an excitation current that affects a common mode magnetic field.

2 . The integrated fluxgate magnetic gradient sensor of claim 1 , wherein the common mode sensitive fluxgate magnetometer further includes a common mode sense wire coil configured to output a voltage proportional to a common mode magnetic field.

3 . The integrated fluxgate magnetic gradient sensor of claim 2 , wherein the voltage across the common mode sense wire coil corresponds to a sum of field change in the first and second cores of the common mode sensitive fluxgate magnetometer.

4 . The integrated fluxgate magnetic gradient sensor of claim 1 , wherein the differential mode sensitive fluxgate magnetometer further includes a differential mode sense wire coil configured to output a voltage proportional to a differential mode magnetic field.

5 . The integrated fluxgate magnetic gradient sensor of claim 4 , wherein the voltage across the differential mode sense wire coil corresponds to a difference in field changes in the third and fourth cores of the differential mode sensitive fluxgate magnetometer.

6 . The integrated fluxgate magnetic gradient sensor of claim 1 , further comprising a differential voltage driver coupled to the common mode sensitive fluxgate magnetometer and the differential mode sensitive fluxgate magnetometer and configured to drive a first compensation current through a first compensation wire coil wrapped around the first core and the second core and a second compensation wire coil wrapped around the third core and the fourth coil.

7 . The integrated fluxgate magnetic gradient sensor of claim 6 , further comprising a single-ended voltage driver coupled to the differential mode sensitive fluxgate magnetometer and configured to drive a second compensation current through the second compensation wire coil.

8 . The integrated fluxgate magnetic gradient sensor of claim 7 , wherein the common mode sensitive fluxgate magnetometer further includes a common mode sense wire coil and an input to the differential voltage driver is a voltage across the common mode sense wire coil.

9 . The integrated fluxgate magnetic gradient sensor of claim 7 , wherein the differential mode sensitive fluxgate magnetometer further includes a differential mode sense wire coil and an input to the single-ended voltage driver is a voltage across the differential mode sense wire coil.

10 . The integrated fluxgate magnetic gradient sensor of claim 7 , further comprising a shunt resistor coupled to the single-ended voltage driver and the second compensation wire coil.

11 . A driver circuit, comprising:
a differential voltage driver configured to drive a differential voltage through a common mode sensitive fluxgate magnetometer and a differential mode sensitive fluxgate magnetometer; and a single-ended voltage driver configured to drive a single-ended voltage through the differential mode sensitive fluxgate magnetometer; wherein an input to the differential voltage driver is a voltage across a common mode sense wire coil included in the common mode sensitive fluxgate magnetometer and an input to the single-ended voltage driver is a voltage across a differential mode sense wire coil included in the differential mode sensitive fluxgate magnetometer.

12 . The driver circuit of claim 11 , further comprising a shunt resistor coupled to an output of the single-ended voltage driver and the differential mode sensitive fluxgate magnetometer.

13 . The driver circuit of claim 11 , wherein the differential voltage driver is configured to drive the differential voltage through the common mode sensitive fluxgate magnetometer by driving the differential voltage through a compensation wire coil wrapped around a magnetic core included in the common mode sensitive fluxgate magnetometer.

14 . The driver circuit of claim 11 , wherein the single-ended voltage driver is configured to drive the single-ended voltage through the differential mode sensitive fluxgate magnetometer by driving the single-ended voltage through a compensation wire coil wrapped around a magnetic core included in the differential mode sensitive fluxgate magnetometer.

15 . The driver circuit of claim 11 , wherein the differential voltage driver is coupled to the common mode sensitive fluxgate magnetometer and the differential mode sensitive fluxgate magnetometer in parallel.

16 . A method of measuring a magnetic field gradient, comprising:
driving, by a differential voltage driver, a differential voltage through a common mode compensation wire coil wrapped around a first core and a second core; driving the differential voltage through a differential mode compensation wire coil wrapped around a third core and a fourth core; driving, by a single-ended voltage driver, a single-ended voltage through the differential mode compensation wire coil; and sensing a magnetic field gradient voltage across a shunt resistor coupled to the single-ended voltage driver and the differential mode compensation wire coil.

17 . The method of claim 16 , further comprising:
sensing a common mode sense voltage across a common mode sense wire coil wrapped around the first and second cores; inputting the common mode sense voltage into the differential voltage driver.

18 . The method of claim 16 , further comprising:
sensing a differential mode sense voltage across a common mode sense wire coil wrapped around the third and fourth cores; inputting the differential mode sense voltage into the single-ended voltage driver.

19 . The method of claim 16 , wherein the first core is adjacent the second core, the third core is adjacent the first core, and the fourth core is adjacent the second core.

20 . The method of claim 16 , wherein the first, second, third, and fourth cores comprise a ferromagnetic material.

Assignees

• Texas Instruments Deutschland

Inventors

• Snoeij Martijn Fridus
• Schäffer Viola
• Haug Gebhard

Classifications

• G01R33/022 Primary

  Measuring gradient · CPC title

• G01R33/04

  using the flux-gate principle · CPC title