METHOD AND APPARATUS FOR REDUCING COMMON MODE VARIATIONS IN A VOLTAGE SENSING COMPONENT

• US 20140210482A1
• Filed: 01/28/2013
• Published: 07/31/2014
• Est. Priority Date: 01/28/2013
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Yu, Baiying, Walker, Brett C.
• Application Number:
  US13/752,314
• Publication Number:
  US 20140210482A1
• Time in Patent Office: Days
• US Class Current: 324/433
• CPC Class Codes: G01R 19/0084 measuring voltage only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: H03F 2200/261 Amplifier which being suitable for instrumentation applications
• CPC Class Codes: H03F 2200/375 Circuitry to compensate the offset being present in an amplifier
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 3/005 using switched capacitors, e.g. dynamic amplifiers; using switched capacitors as resistors in differential amplifiers H03F3/45 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method and apparatus that reduce common mode variations experienced by a voltage sensing component. A measurement component such as a BATFET or an external sensing resistor, receives, at its source, a voltage from the top of a battery having a voltage VPH_PWR. A voltage sensing component, such as an ADC, is powered by the voltage from the battery. A power referenced component, such as a power referenced LDO, tracks the voltage from the battery and outputs the tracked voltage minus a predetermined voltage amount to a negative side of the voltage sensing component.

Claims

1. An apparatus for reducing Common Mode variations experienced by a voltage sensing component, the apparatus comprising:

a battery having a voltage VPH_PWR;

a measurement component that receives, at its source, a voltage from the top of the battery;

a voltage sensing component powered by the voltage from the battery; and

a power referenced component that tracks the voltage from the battery and outputs the tracked voltage from the battery minus a predetermined voltage amount to a negative side of the voltage sensing component.

2. The apparatus of claim 1, wherein the measurement component comprises at least one of a Battery Field Effect Transistor (BATFET) and an external sensing resistor (R_s).

3. The apparatus of claim 2, wherein the power referenced component comprises a power referenced low dropout regulator (LDO).

4. The apparatus of claim 3, wherein the power referenced LDO receives an input voltage from VPH_PWR.

5. The apparatus of claim 3, wherein the voltage sensing component comprises a switched-cap sigma delta ADC powered from VPH_PWR and an output of the LDO.

6. The apparatus of claim 1, wherein the predetermined voltage amount is approximately 1.8 V.

7. The apparatus of claim 1, wherein the measurement component, the voltage sensing component, and the power referenced component are comprised in a power management integrated circuit (PMIC).

8. The apparatus of claim 7, wherein the apparatus is configured to provide a fuel gauge for the battery, and wherein the measurement component outputs a measured voltage Vsense indicating a fuel level of the battery.

9. The apparatus of claim 7, wherein the battery is external to the PMIC and a bypass capacitor connects the LDO to the exterior of the PMIC.

10. The apparatus of claim 1, wherein the apparatus is comprised in a UE.

11. A method of reducing a common mode variation experienced by a voltage sensing component, the method comprising:

receiving a first voltage from a battery at a source of a measurement component, wherein the first voltage is received from the top side of the battery;

outputting a second voltage from the measurement component to a power referenced component, wherein the second voltage tracks the first voltage;

outputting a third voltage from the power referenced component to a voltage sensing component, wherein the third voltage is equal to the second voltage less a predetermined voltage amount; and

powering the voltage sensing component between the first voltage and the second voltage.

12. The method of claim 11, wherein the measurement component comprises at least one of a Battery Field Effect Transistor (BATFET) and an external sensing resistor.

13. The method of claim 12, wherein the power referenced component comprises a power referenced low dropout regulator (LDO).

14. The method of claim 13, wherein the power referenced LDO receives the first voltage as an input voltage.

15. The method of claim 11, wherein the voltage sensing component comprises a Switched-cap sigma delta ADC that receives an output from at least one of between a source and a drain of a BATFET and both sides of an external resistor (R_s).

16. The method of claim 11, wherein the predetermined voltage amount is approximately 1.8 V.

17. The method of claim 11, wherein the measurement component, the voltage sensing component, and the power referenced component are comprised in a power management integrated circuit (PMIC).

18. The method of claim 17, wherein the measurement component is comprised in a fuel gauge for the battery, the method further comprising:

outputting a measured voltage Vsense from the measurement component indicating a fuel level of the battery.

19. The method of claim 18, wherein the PMIC is comprised in a UE.

20. The method of claim 17, wherein the battery is external to the PMIC, and wherein an exterior bypass capacitor connects to the power referenced component.