Magnetic sensor with improved stress compensation accounting for temperature

1. A magnetic field sensor, comprising:

a stress sensing element;

a temperature sensing element;

a magnetic field sensing element that is arranged to generate a sensing element signal;

a memory configured to store a first table, the first table identifying a plurality of stress-to-sensitivity coefficients, each of the plurality of stress-to-sensitivity coefficients being mapped to a different temperature value; and

electronic circuitry configured to: obtain a stress reading by using the stress sensing element, obtain a temperature reading by using the temperature sensing element, use the temperature reading and the stress reading to calculate a stress difference, obtain a stress-to-sensitivity coefficient that corresponds to the temperature reading by using the first table, calculate a gain adjustment coefficient based on the stress-to-sensitivity coefficient, and adjust a gain of the sensing element signal based on the gain adjustment coefficient,

wherein the stress difference includes a difference between an expected stress and the stress reading that is obtained from the stress sensing element.

2. The magnetic field sensor of claim 1 , wherein calculating the stress difference includes:

identifying a temperature segment that corresponds to the temperature reading;

identifying a first expected stress that corresponds to a lower bound of the temperature segment;

identifying a second expected stress that corresponds to an upper bound of the temperature segment;

interpolating the first expected stress and the second expected stress to produce a third expected stress; and

calculating a difference between the third expected stress and the stress reading.

3. The magnetic field sensor of claim 2 , wherein the first expected stress and the second expected stress are identified by searching a second table that is stored in the memory, the second identifying a plurality of temperature-stress pairs, each temperature stress pair including a temperature value and an expected stress that corresponds to the temperature value.

4. The magnetic field sensor of claim 2 , wherein the temperature segment is identified based on a plurality of temperature values that are available in a second table that is stored in the memory, the second table identifying a different expected stress for each of the plurality of temperature values.

5. The magnetic field sensor of claim 2 , wherein the lower bound of the temperature segment includes a temperature value that is smaller than the temperature reading, and the upper bound of the temperature segment includes a temperature value that is greater than the temperature reading.

6. The magnetic field sensor of claim 1 , wherein:

the electronic circuitry includes a processor coupled to a gain adjustable circuit,

the processor is configured to generate a gain correction signal based on the gain adjustment coefficient, and

the gain adjustable circuit is configured to receive: (i) the gain correction signal and (ii) adjust the gain of the sensing element signal based on the gain correction signal.

7. The magnetic field sensor of claim 1 , wherein the electronic circuitry includes a processor and the gain of the sensing element signal is adjusted in the digital domain.

8. The magnetic field sensor of claim 1 , wherein the magnetic field sensing element includes at least one of a Hall effect element and a magnetoresistive element.

9. A method comprising

obtaining a temperature reading by using a temperature sensing element that is part of a magnetic field sensor;

obtaining a stress reading by using a stress sensing element that is part of the magnetic field sensor;

calculating a stress difference using the temperature reading and the stress reading, the stress difference including a difference between an expected stress that corresponds to the temperature reading and the stress reading obtained from the stress sensing element; and

adjusting a gain of a sensing element signal based on the stress difference, the sensing element signal being generated at least in part by a magnetic field sensing element that is part of the magnetic field sensor.

10. The method of claim 9 , wherein adjusting the gain of the sensing element signal includes:

identifying at least one stress-to-sensitivity coefficient based on the temperature reading;

obtaining at least one gain adjustment coefficient based on the stress-to-sensitivity coefficient; and

generating a gain correction signal based on the gain adjustment coefficient and feeding the gain correction signal to a gain adjustable circuit that is arranged to adjust the gain of the sensing element signal.

11. The method of claim 9 , wherein calculating the stress difference includes:

identifying a temperature segment that corresponds to the temperature reading;

identifying a first expected stress that corresponds to a lower bound of the temperature segment;

identifying a second expected stress that corresponds to an upper bound of the temperature segment;

interpolating the first expected stress and the second expected stress to produce a third expected stress; and

calculating a difference between the third expected stress and the stress reading.

12. The method of claim 11 , wherein the temperature segment is identified based on a plurality of temperature values that are available in an expected stress table, the expected stress table identifying a different expected stress for each of the plurality of temperature values, the expected stress table being stored in a memory of the magnetic field sensor.

13. The method of claim 9 , wherein the gain of the sensing element signal is adjusted in the digital domain.

14. The method of claim 9 , wherein the magnetic field sensing element includes at least one of a Hall effect element and a magnetoresistive element.

15. A magnetic field sensor, comprising:

a temperature sensing element;

a stress sensing element;

a magnetic field sensing element; and

electronic circuitry configured to perform the operations of:

obtaining a temperature reading by using the temperature sensing element;

obtaining a stress reading by using the stress sensing element;

calculating a stress difference using the temperature reading and the stress reading, the stress difference including a difference between an expected stress that corresponds to the temperature reading and the stress reading obtained from the stress sensing element; and

adjusting a gain of a sensing element signal based on the stress difference, the sensing element signal being generated by the magnetic field sensing element.

16. The magnetic field sensor of claim 15 , wherein:

the electronic circuitry includes a processor that is operatively coupled to a gain adjustable circuit, the gain adjustable circuit that is arranged to adjust the gain of the sensing element signal, and

adjusting the gain of the sensing element signal includes:

identifying, by the processor, at least one stress-to-sensitivity coefficient based on the temperature reading;

obtaining, by the processor, at least one gain adjustment coefficient based on the stress-to-sensitivity coefficient; and

generating, by the processor, a gain correction signal based on the gain adjustment coefficient and feeding the gain correction signal to the gain adjustable circuit.

17. The magnetic field sensor of claim 16 , wherein the magnetic field sensing element includes at least one of a Hall effect element and a magnetoresistive element.

18. The magnetic field sensor of claim 15 , wherein calculating the stress difference includes:

identifying a temperature segment that corresponds to the temperature reading;

identifying a first expected stress that corresponds to a lower bound of the temperature segment;

identifying a second expected stress that corresponds to an upper bound of the temperature segment;

interpolating the first expected stress and the second expected stress to produce a third expected stress; and

calculating a difference between the third expected stress and the stress reading.

19. The magnetic field sensor of claim 18 , wherein the temperature segment is identified based on a plurality of temperature values that are available in an expected stress table, the expected stress table identifying a different expected stress for each of the plurality of temperature values, the expected stress table being stored in a memory of the magnetic field sensor.

20. The magnetic field sensor of claim 15 , wherein the gain of the sensing element signal is adjusted in the digital domain.