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

• US 7,106,137 B2
• Filed: 06/30/2004
• Issued: 09/12/2006
• 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.
• Primary Examiner(s): NGUYEN, PATRICIA T
• Application Number:
  US10/880,962
• Publication Number:
  US 20050030100A1
• Time in Patent Office: 804 Days
• Field of Search: 330/297, 330/296, 330/129, 330/285
• 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 method of controlling the output power of a power amplifier comprising:

sensing the power amplifier supply voltage;

sensing the power amplifier supply current;

while the output voltage of the power amplifier is below a threshold level, using the sensed power amplifier supply current to regulate the supply current of the power amplifier to maintain a desired power amplifier output power level; and

while the output voltage of the power amplifier is above a threshold level, using the sensed power amplifier supply voltage to regulate the supply voltage of the power amplifier to maintain a desired power amplifier output power level.

2. The method of claim 1, further comprising:

generating a first signal based on the sensed power amplifier supply voltage; and

generating a second signal based on the sensed power amplifier supply current.

3. The method of claim 2, wherein the output power is control led using the signal having the lower voltage level.

4. The method of claim 2 wherein the first signal is used to control the output power of the power amplifier while the output voltage of the power amplifier is above a threshold level, and the second signal is used to control the output power of the power amplifier while the output voltage of the power amplifier is below a threshold level.

5. The method of claim 1, further comprising using a power control signal with the sensed power amplifier supply voltage or the sensed power amplifier supply current to control the output power of the power amplifier.

6. A power regulator for supplying regulated power to a power amplifier, the power regulator comprising:

a voltage regulator configured to provide a regulated supply voltage to a power amplifier;

a current regulator configured to provide a regulated supply current to a power amplifier;

control circuitry coupled to the voltage regulator and to the current regulator for controlling the operation of the voltage regulator and the current regulator;

wherein, over a first power amplifier output voltage range, the control circuitry uses the voltage regulator and a power control signal to regulate the supply voltage to the power amplifier; and

wherein, over a second power amplifier output voltage range, the control circuitry uses the current regulator and the power control signal to regulate the supply current to the power amplifier.

7. The power regulator of claim 6, wherein the control circuitry uses the voltage regulator at high output power levels, and uses the current regulator at low output power levels.

8. The power regulator of claim 6, further comprising a voltage sensor and a current sensor.

9. The power regulator of claim 8, 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.

10. The power regulator of claim 8, wherein the voltage sensor generates a first signal and the current sensor generates a second signal.

11. The power regulator of claim 10, wherein the control circuitry uses either the first or second signals to control the output power of the power amplifier.

12. The power regulator of claim 11, wherein the control circuitry uses the signal having the lower voltage level to control the output power of the power amplifier.

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

sensing the power amplifier supply voltage;

sensing the power amplifier supply current;

comparing the sensed power amplifier supply voltage and the sensed power amplifier supply current; and

regulating the supply voltage of the power amplifier based on a desired power amplifier output power level, and on the comparison of the sensed power amplifier supply voltage and the sensed power amplifier supply current.

14. The method of claim 13, further comprising:

generating a first signal based on the sensed power amplifier supply voltage; and

generating a second signal based on the sensed power amplifier supply current.

15. The method of claim 14, wherein the supply voltage of the power amplifier is regulated using the lower of the first and second signals.

16. The method of claim 14, wherein the first signal is used to regulate the output voltage of the power amplifier while the output voltage of the power amplifier is above a threshold level, and the second signal is used to regulate the output voltage of the power amplifier while the output voltage of the power amplifier is below a threshold level.

17. The method of claim 13, further comprising using a power control signal with the sensed power amplifier supply voltage or the sensed power amplifier supply current to control the output voltage of the power amplifier.

18. The method of claim 13, wherein the supply voltage of the power amplifier is regulated using the sensed power amplifier supply voltage at high output power levels, and using the sensed power amplifier supply current at low output power levels.