Stress compensation systems and methods in differential sensors

Patent metadata

Field	Value
Publication number	US-9410820-B2
Application number	US-201213540081-A
Country	US
Kind code	B2
Filing date	Jul 2, 2012
Priority date	Jul 2, 2012
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

Embodiments relate to stress compensation in differential sensors. In an embodiment, instead of compensating for stress on each sensor element independently, stress compensation circuitry aims to remove stress-related mismatch between two sensor elements using the sensor elements themselves to detect the mismatch. A circuit can be implemented in embodiments to detect mechanical stress-related mismatch between sensor elements using the sensor elements, and tune the output signal by a compensation factor to eliminate the mismatch. Embodiments are therefore less complicated and less expensive than conventional approaches. While embodiments have applicability to virtually any differential sensor, including magnetic field, pressure, temperature, current and speed, an example embodiment discussed herein relates to magnetic field.

First claim

What is claimed is:

1. A differential magnetic field sensor system comprising:
at least two sensor elements configured to sense a magnetic field characteristic;
compensation circuitry coupled to the at least two sensor elements to use the at least two sensor elements to sense a mechanical stress affecting the at least two sensor elements and configured to determine a compensation factor that is a function of a difference in mechanical stress between the at least two sensor elements; and
a sensor system output configured to provide an output signal that is a difference between the outputs of the at least two sensor elements adjusted by the compensation factor.

2. The differential magnetic field sensor system of claim 1 , wherein the compensation factor substantially eliminates a sensitivity mismatch between the at least two sensor elements caused by mechanical stress on the at least two sensor elements.

3. The differential magnetic field sensor system of claim 1 , wherein the difference in mechanical stress between the at least two sensor elements is estimated from a difference in supply voltages of the at least two sensor elements.

4. The differential magnetic field sensor system of claim 1 , wherein the difference in mechanical stress between the at least two sensor elements is estimated from a difference in supply currents of the at least two sensor elements.

5. The differential magnetic field sensor system of claim 1 , further comprising a die, wherein the at least two sensor elements are positioned spaced apart on the die.

6. The differential magnetic field sensor system of claim 1 , further comprising first and second dies, wherein a first of the at least two sensor elements is positioned on the first die and a second of the at least two sensor elements is positioned on the second die.

7. The differential magnetic field sensor system of claim 1 , wherein the compensation circuitry comprises an analog-to-digital (A/D) converter.

8. The differential magnetic field sensor system of claim 1 , wherein the compensation circuitry comprises at least one temperature sensor.

9. The differential magnetic field sensor system of claim 8 , wherein a first temperature sensor is associated with a first of the at least two sensor elements and a second temperature sensor is associated with a second of the at least two sensor elements.

10. The differential magnetic field sensor system of claim 1 , wherein the compensation circuitry comprises at least one temperature sensor, and wherein the compensation factor is based in part on an output of the at least one temperature sensor.

11. The differential magnetic field sensor system of claim 1 , wherein the differential magnetic field sensor system is a differential Hall sensor system.

12. A stress compensation method for a differential magnetic field sensor comprising:
determining a compensation factor that is a function of a difference in mechanical stress between at least two sensor elements of the differential magnetic field sensor, wherein the at least two sensor elements are used to detect the difference in mechanical stress; and
compensating for a mechanical stress sensitivity mismatch between the at least two sensor elements by adjusting a difference in output signals of the at least two sensor elements by the compensation factor.

13. The method of claim 12 , wherein the difference in mechanical stress between the at least two sensor elements is estimated from a difference in the supply voltages of the at least two sensor elements.

14. The method of claim 12 , wherein the differential magnetic field sensor is a differential Hall sensor.

15. The method of claim 12 , wherein determining a compensation factor further comprises utilizing at least one temperature sensor.

16. The method of claim 15 , wherein utilizing at least one temperature sensor further comprises utilizing a first temperature sensor with a first one of the at least two sensor elements and utilizing a second temperature sensor with a second one of the at least two sensor elements.

Assignees

• Ausserlechner Udo
• Motz Mario
• Infineon Technologies Ag

Inventors

• Ausserlechner Udo
• Motz Mario

Classifications

• G01D3/021 Primary

  using purely analogue techniques · CPC title