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

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

a voltage sensor;

a current sensor;

a resistive element, wherein the current sensor senses current through the resistive element;

a switching device coupled between the resistive element and a voltage source; 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. A power regulator for use with a power amplifier, the power regulator comprising:

a voltage sensor, wherein the voltage sensor generates a first signal;

a voltage regulator;

a current sensor, wherein the current sensor generates a second signal;

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, wherein the control circuitry uses either the first or second signals at any one time to control the output power of the power amplifier, wherein the control circuitry uses the signal having the lower voltage level to control the output power of the power amplifier, and 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.

13. The power regulator of claim 12 , 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.

14. The power regulator of claim 12 , wherein the control circuitry uses the voltage regulator at high output power levels, and uses the current regulator at low output power levels.

15. The power regulator of claim 12 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.

16. The circuit of claim 12 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.

17. An integrated circuit comprising:

a power amplifier;

a voltage sensor, wherein the voltage sensor generates a first signal relating to the sensed voltage;

a current sensor, wherein the current sensor generates a second signal relating to the sensed current; 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, wherein the control circuitry uses the generated signals to control the output power of the power amplifier, and wherein the control circuitry uses the generated signal with the lesser voltage level to control the output power of the power amplifier.

18. The integrated circuit of claim 17 wherein the control circuitry uses the first signal to control the output power of the power amplifier at high power levels.

19. The integrated circuit of claim 18 , wherein the control circuitry uses the second signal to control the output power of the power amplifier at low power levels.

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

providing a voltage sensor to generate a first signal;

providing a voltage regulator;

providing a current sensor to generate a second signal;

providing a current regulator; and

controlling the output power of the power amplifier using either the first or second signals, wherein the output power is controlled using the signal having the lower voltage level, and wherein the output power is controlled using the voltage regulator at high power levels and using the current regulator at low power levels.

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

a voltage sensor, wherein the voltage sensor generates a first signal relating to the sensed voltage;

a current sensor, wherein the current sensor generates a second signal relating to the sensed current; and

control circuitry coupled to the voltage sensor and the current sensor for controlling the output power of the power amplifier, wherein the control circuitry uses the generated signals to control the output power of the power amplifier, and wherein the control circuitry uses the generated signal with the lesser voltage level to control the output power of the power amplifier.

22. The circuit of claim 21 , 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.

23. The circuit of claim 22 , 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.

24. The circuit of claim 22 , 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.

25. The circuit of claim 21 , wherein the control circuitry uses the first signal to control the output power of the power amplifier at high power levels.

26. The 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 circuit of claim 21 , wherein the control circuitry generates a third signal based on the first and second signals.

28. The circuit of claim 27 , 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.

29. The circuit of claim 21 , 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.

30. The circuit of claim 21 , further comprising a resistive element, wherein the current sensor senses current through the resistive element.

31. The circuit of claim 30 , further comprising a switching device coupled between the resistive element and a voltage source.

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

a voltage sensor, wherein the voltage sensor generates a first signal relating to the sensed voltage;

a current sensor, wherein the current sensor generates a second signal relating to the sensed current; and

control circuitry coupled to the voltage sensor and the current sensor for controlling the output power of the power amplifier, wherein the control circuitry uses the generated signals to control the output power of the power amplifier, wherein the control circuitry generates a third signal based on the first and second signals, and 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.

33. The circuit of claim 32 , 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.

34. The circuit of claim 33 , 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.

35. The circuit of claim 33 , 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.

36. The circuit of claim 32 , wherein the control circuitry uses the generated signal with the lesser voltage level to control the output power of the power amplifier.

37. The circuit of claim 32 , wherein the control circuitry uses the first signal to control the output power of the power amplifier at high power levels.

38. The circuit of claim 37 , wherein the control circuitry uses the second signal to control the output power of the power amplifier at low power levels.

39. The circuit of claim 32 , 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.

40. The circuit of claim 32 , further comprising a resistive element, wherein the current sensor senses current through the resistive element.

41. The circuit of claim 40 , further comprising a switching device coupled between the resistive element and a voltage source.