Method and device for improved accuracy of proximity and touch detection in mobile devices

1. A method of detecting proximity, comprising:

providing a mobile device including a proximity sensor;

coupling a capacitive sensing element to the proximity sensor;

determining a compensation value of the proximity sensor;

comparing the compensation value to a reference compensation value to determine validity of the compensation value; and

adjusting a voltage potential of the proximity sensor proportionally to the compensation value.

2. The method of claim 1 , wherein adjusting the voltage potential of the proximity sensor includes adjusting a capacitance of the proximity sensor based on the compensation value.

3. The method of claim 1 , further including:

coupling the voltage potential to an analog-to-digital converter to generate a digital representation of the voltage potential; and

adjusting the digital representation based on a temperature of the mobile device.

4. The method of claim 1 , further including comparing the adjusted voltage potential to a threshold to determine proximity of an object to the mobile device.

5. The method of claim 1 , further including calculating a coefficient defining a relationship between a capacitance of the proximity sensor and a temperature of the mobile device.

6. A method of detecting proximity, comprising:

providing a mobile device including a proximity sensor;

determining a compensation value of the proximity sensor;

determining validity of the compensation value by comparing the compensation value to a reference compensation value; and

adjusting a capacitor bank of the proximity sensor based on the compensation value after determining the compensation value is valid.

7. The method of claim 6 , further including determining proximity of an object to the mobile device by measuring a capacitance of the proximity sensor.

8. The method of claim 6 , further including adjusting a reading of the proximity sensor based on a temperature of the mobile device.

9. The method of claim 6 , further including comparing the adjusted reading to a threshold to determine proximity of an object to the mobile device.

10. The method of claim 6 , further including determining a coefficient defining a relationship between a capacitance of the proximity sensor and a temperature of the mobile device.

11. The method of claim 10 , further including:

measuring the capacitance of the proximity sensor;

measuring the temperature of the mobile device; and

adjusting a value of the capacitance of the proximity sensor based on the coefficient and the temperature of the mobile device.

12. The method of claim 6 , further including providing an analog-to-digital converter to generate a digital representation of the adjusted reading of the proximity sensor, wherein the adjusted reading of the proximity sensor is an analog voltage potential reduced based on the compensation value.

13. A method of detecting proximity, comprising:

providing a proximity sensor;

determining a reference compensation value of the proximity sensor;

comparing a first proximity reading to the reference compensation value to evaluate the first proximity reading as a valid compensation value or an invalid compensation value;

adjusting subsequent readings of the proximity sensor using the first proximity reading if the first proximity reading is a valid compensation value; and

comparing a second proximity reading to the reference compensation value to evaluate the second proximity reading as a valid compensation value or an invalid compensation value if the first proximity reading is an invalid compensation value.

14. The method of claim 13 , wherein adjusting subsequent readings of the proximity sensor includes:

providing a bank of capacitors; and

adjusting the bank of capacitors based on the first proximity reading.

15. The method of claim 13 , further including adjusting subsequent readings of the proximity sensor based on a temperature sensor.

16. The method of claim 13 , further including adjusting a radio frequency signal based on the subsequent readings of the proximity sensor.

17. The method of claim 13 , further including determining a coefficient defining a relationship between a capacitance of the proximity sensor and a temperature of the proximity sensor.

18. The method of claim 17 , further including adjusting subsequent readings of the proximity sensor using the coefficient and the temperature of the proximity sensor.

19. A proximity sensor, comprising:

a reference compensation value of the proximity sensor;

a comparator for comparing a measured compensation value to the reference compensation value;

an offset compensation configured to reduce a voltage potential of the proximity sensor based on the measured compensation value; and

an analog-to-digital converter including an input coupled to the voltage potential.

20. The proximity sensor of claim 19 , further including a temperature sensor coupled to the proximity sensor.

21. The proximity sensor of claim 19 , wherein the offset compensation further includes a bank of capacitors controlled by the measured compensation value.

22. The proximity sensor of claim 19 , further including a digital processor coupled to an output of the analog-to-digital converter.