METHOD AND APPARATUS FOR TEMPERATURE ADJUSTED CONTROL OF BATFET CURRENT SENSING

• US 20140028285A1
• Filed: 07/25/2012
• Published: 01/30/2014
• Est. Priority Date: 07/25/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Yu, Baiying, Stockstad, Troy, Mikuteit, Eric I., Bajaj, Nihit
• Granted Patent: US 9,000,750 B2
• Time in Patent Office: Days
• US Class Current: 324/105
• CPC Class Codes: G01R 11/185 Temperature compensation
• CPC Class Codes: G01R 19/0092 measuring current only all subgroups of G01R19/00 take precedence

Abstract

A method and apparatus for providing a temperature sensing loop used in connection with a current sensing component, such as a BATFET, in order to compensate for variations in the BATFET'"'"'s resistance due to temperature variations. The temperature sensing loop detects a temperature of the BATFET and regulates the gate voltage of the BATFET based on the detected temperature in order to compensate for changes in the BATFET'"'"'s resistance. The temperature sensing feedback loop maintains the BATFET at a constant resistance for current sensing through negative feedback control. The BATFET and temperature sensing loop can be provided as components of an on-chip fuel gauging application for a UE.

Claims

1. An apparatus for temperature adjusted control for a current sensing component, comprising:

a current sensing component inserted in a voltage line, wherein the current sensing component measures current in the voltage line; and

a feedback loop component that tracks a temperature of the current sensing component and modulates a resistance of the current sensing component based on the tracked temperature.

2. The apparatus of claim 1, wherein the current sensing component comprises one of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) and a Battery Field-Effect Transistor (BATFET).

3. The apparatus of claim 2, wherein the current sensing component comprises a BATFET, and wherein the feedback loop component detects a temperature of the BATFET and modulates a gate voltage of the BATFET based on the detected temperature.

4. The apparatus of claim 3, wherein the BATFET receives a first voltage in the voltage line, and wherein the feedback loop component comprises:

a BATFET replica that receives the first voltage and outputs a second voltage;

a programmable resistor that receives the first voltage and outputs a third voltage;

an error amplifier that receives the second voltage and the third voltage and outputs a fourth voltage;

and a second amplifier that receives the fourth voltage and outputs a fifth voltage to a gate of the BATFET.

5. The apparatus of claim 3, wherein the BATFET receives a first voltage in the voltage line, and wherein the feedback loop component comprises:

a BATFET replica that receives the first voltage and outputs a second voltage, wherein the BATFET replica comprises a plurality of field effect transistors (FET) in series such that a sense point of the BATFET replica is programmable by selecting an amount of the FETs used in the BATFET replica;

an error amplifier that receives the second voltage and the third voltage and outputs a fourth voltage;

and a second amplifier that receives the fourth voltage and outputs a fifth voltage to a gate of the BATFET.

6. The apparatus of claim 5, wherein the error amplifier comprises a switch cap integrator.

7. The apparatus of claim 5, wherein the BATFET is configured to receive a high side voltage from a battery at a source of the BATFET.

8. The apparatus of claim 7, wherein the BATFET measures the fuel level of the battery.

9. The apparatus of claim 8, wherein the apparatus is comprised in a UE.

10. The apparatus of claim 9, wherein the apparatus is comprised in a power management integrated circuit (PMIC) of the UE.

11. The apparatus of claim 1, wherein the feedback loop component modulates the resistance of the current sensing component based on the tracked temperature in order to regulate the resistance of the current sensing component to a substantially constant resistance.

12. A method of adjusting a resistance of a current sensing component to adjust for temperature and process variations, the method comprising:

receiving a first voltage at a current sensing component inserted in a voltage line;

detecting a temperature of the current sensing component via a feedback loop component; and

adjusting a resistance of the current sensing component via the feedback loop component based on the detected temperature.

13. The method of claim 12, wherein the current sensing component comprises one of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) and a Battery Field-Effect Transistor (BATFET).

14. The method of claim 13, wherein the current sensing component comprises a BATFET, the method further comprising:

modulating a gate voltage of the BATFET based on the detected temperature in order to adjust the resistance of the BATFET.

15. The method of claim 13, further comprising

receiving the first voltage at a BATFET replica that outputs a second voltage;

receiving the first voltage at a programmable resistor that outputs a third voltage;

amplifying a difference between the second voltage and the third voltage at an error amplifier that outputs a fourth voltage;

receiving the fourth voltage at a track and hold amplifier; and

outputting a fifth voltage from the track and hold amplifier to a gate of the BATFET.

16. The method of claim 14, further comprising

receiving the first voltage at a BATFET replica that outputs a second voltage, wherein the BATFET replica comprises a plurality of field effect transistors (FET) in series;

adjusting a sense point of the BATFET replica by selecting an amount of the FETs used in the BATFET replica;

amplifying a difference between the second voltage and the third voltage at an error amplifier that outputs a fourth voltage;

receiving the fourth voltage at a track and hold amplifier; and

outputting a fifth voltage from the track and hold amplifier to a gate of the BATFET.

17. The method of claim 16, wherein the error amplifier comprises a switch cap integrator.

18. The method of claim 16, wherein the first voltage is a high side voltage from a battery.

19. The method of claim 18, further comprising:

measuring a fuel level of the battery based on an output from the BATFET.

20. The method of claim 19, wherein the BATFET and feedback loop are comprised in a UE.

21. The method of claim 20, wherein the BATFET and feedback loop are comprised in a power management integrated circuit (PMIC) of the UE.

22. The method of claim 12, wherein the resistance of the current sensing component is programmed in segments through digital control to reduce process variation, the method further comprising:

performing a single calibration to eliminate process variation in the resistance of the current sensing component.

23. The method of claim 12, wherein the resistance of the current sensing component is adjusted based on the tracked temperature in order to regulate the resistance of the current sensing component to a substantially constant resistance.