Method and apparatus for controlling the output power of a power amplifier

• US 20040174218A1
• Filed: 03/04/2003
• Published: 09/09/2004
• Est. Priority Date: 03/04/2003
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Dupuis, Timothy J., Bocock, Ryan M.
• Granted Patent: US 6,897,730 B2
• Time in Patent Office: Days
• US Class Current: 330/285
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 2200/462 the current being sensed
• CPC Class Codes: H03F 2200/471 the voltage being sensed
• CPC Class Codes: H03F 2200/481 A resistor being used as sensor
• CPC Class Codes: H03F 2200/504 the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier
• CPC Class Codes: H03F 2200/78 A comparator being used in a controlling circuit of an amplifier
• CPC Class Codes: H03G 3/004 Control by varying the supply voltage

Abstract

A method and apparatus is provided for use with a power amplifier to provide a regulated supply to the power amplifier. The invention uses a combination of voltage and current regulation to overcome the problems encountered in the prior art. In one example, voltage regulation is used at high power levels, while current regulation is used at low power levels.

Claims

1. A circuit for controlling the output power of a power amplifier comprising:

a voltage sensor;

a current sensor; and

control circuitry coupled to the voltage sensor and the current sensor for controlling the output power of the power amplifier.

2. The circuit of claim 1, further comprising:

a voltage regulator; and

a current regulator; and

wherein the output power of the power amplifier is regulated using either the voltage regulator or the current regulator.

3. The circuit of claim 2, wherein the output power of the power amplifier is regulated using the voltage regulator at a first output power level range and using the current regulator at a second output power level range.

4. The circuit of claim 2, wherein the output power of the power amplifier is regulated using the voltage regulator at high output power levels and using the current regulator at low output power levels.

5. The circuit of claim 1, wherein the voltage sensor generates a first signal relating to the sensed voltage and the current sensor generates a second signal relating to the sensed current, and wherein the control circuitry uses the generated signals to control the output power of the power amplifier.

6. The circuit of claim 5, wherein the control circuitry uses the generated signal with the lesser voltage level to control the output power of the power amplifier.

7. The circuit of claim 5, wherein the control circuitry uses the first signal to control the output power of the power amplifier at high power levels.

8. The circuit of claim 7, wherein the control circuitry uses the second signal to control the output power of the power amplifier at low power levels.

9. The circuit of claim 5, wherein the control circuitry generates a third signal based on the first and second signals.

10. The circuit of claim 9, wherein the third signal approximates the first signal over a first output power level range and approximates the second signal over a second output power level range.

11. The circuit of claim 1, further comprising a switching device coupled between a voltage source and the power amplifier, wherein the voltage sensor senses a voltage present between the power amplifier and the switching device.

12. The circuit of claim 1, further comprising a resistive element, wherein the current sensor senses current through the resistive element.

13. The circuit of claim 12, further comprising a switching device coupled between the resistive element and a voltage source.

14. A power regulator for use with a power amplifier, the power regulator comprising:

a voltage regulator;

a current regulator; and

control circuitry coupled to the voltage regulator and to the current regulator for regulating the output power of the power amplifier using the voltage regulator and the current regulator.

15. The power regulator of claim 14, wherein the control circuitry uses the voltage regulator during a first output power range, and uses the current regulator during a second output power range.

16. The power regulator of claim 14, wherein the control circuitry uses the voltage regulator at high output power levels, and uses the current regulator at low output power levels.

17. The power regulator of claim 14, further comprising a voltage sensor and a current sensor.

18. The power regulator of claim 17, wherein the control circuitry regulates the output power of the power amplifier based on voltage sensed by the voltage sensor and current sensed by the current sensor.

19. The power regulator of claim 17, wherein the voltage sensor generates a first signal and the current sensor generates a second signal.

20. The circuit of claim 19, wherein the control circuitry uses either the first or second signals at any one time to control the output power of the power amplifier.

21. The circuit of claim 20, wherein the control circuitry uses the signal having the lower voltage level to control the output power of the power amplifier.

22. The circuit of claim 21, wherein the control circuitry uses the first signal to control the output power of the power amplifier during high power levels and the second signal to control the output power of the power amplifier during low power levels.

23. An integrated circuit comprising:

a power amplifier;

a voltage sensor;

a current sensor; and

control circuitry coupled to the voltage sensor and the current sensor for controlling the output power of the power amplifier using information from the voltage and current sensors.

24. The integrated circuit of claim 23, wherein the voltage sensor generates a first signal relating to the sensed voltage and the current sensor generates a second signal relating to the sensed current, and wherein the control circuitry uses the generated signals to control the output power of the power amplifier.

25. The integrated circuit of claim 24, wherein the control circuitry uses the first signal to control the output power of the power amplifier at high power levels.

26. The integrated circuit of claim 25, wherein the control circuitry uses the second signal to control the output power of the power amplifier at low power levels.

27. The integrated circuit of claim 24, wherein the control circuitry uses the generated signal with the lesser voltage level to control the output power of the power amplifier.

28. A method of controlling the output power of a power amplifier comprising:

providing a voltage regulator;

providing a current regulator; and

controlling the output power of a power amplifier using the voltage regulator at high power levels and using the current regulator at low power levels.

29. The power regulator of claim 28, further comprising the steps of:

providing a voltage sensor to generate a first signal; and

providing a current sensor to generate a second signal.

30. The power regulator of claim 29, further comprising the step of controlling the output power of the power amplifier using either the first or second signals.

31. The power regulator of claim 30, wherein the output power is controlled using the signal having the lower voltage level.

32. The power regulator of claim 30, wherein the first signal is used to control the output power of the power amplifier during high power levels and the second signal is used to control the output power of the power amplifier during low power levels.

33. A method of controlling the output power of a power amplifier comprising:

sensing current provided to the power amplifier;

sensing voltage provided to the power amplifier;

selectively using the sensed current and sensed voltage to control the output power of the power amplifier.

34. The method of claim 33, wherein at high power levels, the sensed voltage is used to control the output power of the power amplifier.

35. The method of claim 33, wherein at low power levels, the sensed current is used to control the output power of the power amplifier.

36. The method of claim 33, wherein the sensed voltage is used to control the power amplifier during a first output power level range and the sensed current is used to control the power amplifier during a second output power level range.

37. The method of claim 33, further comprising the steps of providing a voltage regulator and providing a current regulator, wherein the voltage regulator is used at high power levels and the current regulator is used at low power levels.