Transmitter with an envelope tracking power amplifier utilizing digital predistortion of the signal envelope

• US 20060209984A1
• Filed: 12/17/2004
• Published: 09/21/2006
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew Corporation (CommScope Holding Company, Inc.)
• Inventors: Kenington, Peter Blakeborough
• Granted Patent: US 7,706,467 B2
• Time in Patent Office: Days
• US Class Current: 375/297
• CPC Class Codes: H03F 1/0222 by using a signal derived from the input signal
• CPC Class Codes: H03F 2200/102 A non-specified detector of a signal envelope being used in an amplifying circuit

Abstract

A transmitter comprises an amplifier operable for receiving an input signal and amplifying the input signal to produce an output signal. A power supply is coupled to the amplifier for supplying power to the amplifier, the power supply operable for tracking the input signal and varying the level of power supplied to the amplifier in response to variation of the input signal. A predistortion circuit is coupled to the power supply, the predistortion circuit operable for receiving the input signal and predistorting the input signal to the power supply for addressing input signal tracking capabilities of the power supply.

Claims

1. A transmitter comprising:

an amplifier operable for receiving an input signal and amplifying the input signal to produce an output signal;

a power supply coupled to the amplifier for supplying power to the amplifier, the power supply operable for tracking the input signal and varying the level of power supplied to the amplifier in response to variation of the input signal;

a predistortion circuit coupled to the power supply, the predistortion circuit operable for receiving the input signal and predistorting the input signal to the power supply for addressing input signal tracking capabilities of the power supply.

2. The transmitter of claim 1 wherein the power supply is operable for tracking the input signal envelope.

3. The transmitter of claim 2 wherein the predistortion circuit is operable for predistorting the input signal envelope.

4. The transmitter of claim 1 wherein the predistortion circuit is operable for predistorting the input signal for addressing at least one of non-linearities and slew rate limitations of the power supply.

5. The transmitter of claim 1 wherein the predistortion circuit is a digital predistortion circuit.

6. The transmitter of claim 5 wherein the digital predistortion circuit includes at least one of a Look Up Table circuit or a Polynomial-based circuit.

7. The transmitter of claim 1 wherein the predistortion circuit is an analog predistortion circuit.

8. The transmitter of claim 7 wherein the analog predistortion circuit includes at least one of a diode, a transistor, or an amplifier.

9. The transmitter of claim 1 wherein the predistortion circuit is operable for predistorting the input signal to cause over compensation in the level of power supplied to the amplifier by the power supply to ensure proper amplification.

10. The transmitter of claim 9 wherein the overcompensation caused by the predistortion is related to the level of an input signal envelope.

11. The transmitter of claim 1 wherein the predistortion circuit is adaptable for varying the predistortion of the input signal to maintain proper amplification based on the variation of operational parameters for circuit components of at least one of the amplifier, power supply or predistortion circuit.

12. The transmitter of claim 1 wherein the power supply varies the level of power supplied to the amplifier by varying drain voltage at the amplifier, the predistortion circuit being operable for predistorting the input signal to cause the level of power supplied to the amplifier to meet or exceed a required drain voltage.

13. The transmitter of claim 1 wherein the predistortion circuit is adaptable, and further comprising signal processing circuitry coupled to the predistortion circuit for adapting the predistortion circuit based on at least one of the input signal and the output signal.

14. The transmitter of claim 1 wherein the predistortion circuit is adaptable, and further comprising signal processing circuitry coupled to the predistortion circuit for adapting the predistortion circuit based on at least one of the input signal and a tracking output signal of the power supply.

15. A transmitter comprising:

an amplifying circuit for amplifying an input signal to produce an output signal;

a power supply operable for varying the level of power supplied to the amplifier in response to variation of an input signal envelope directed to the power supply;

a predistortion circuit operable for receiving and predistorting the input signal envelope before it is directed to the power supply for addressing envelope tracking capabilities of the power supply.

16. The transmitter of claim 15 wherein the predistortion circuit is operable for predistorting the input signal envelope for addressing at least one of non-linearities or slew rate limitations of the power supply.

17. The transmitter of claim 15 wherein the predistortion circuit is a digital predistortion circuit.

18. The transmitter of claim 17 wherein the digital predistortion circuit includes at least one of a Look Up Table circuit or a Polynomial-based circuit.

19. The transmitter of claim 15 wherein the predistortion circuit is an analog predistortion circuit.

20. The transmitter of claim 15 wherein the predistortion circuit is operable for predistorting the input signal envelope to cause over compensation in the level of power supplied to the amplifier by the power supply to ensure proper amplification.

21. The transmitter of claim 15 wherein the predistortion circuit is adaptable for varying the predistortion of the input signal to maintain proper amplification based on the variation of operational parameters for circuit components of at least one of the amplifier, power supply or predistortion circuit.

22. The transmitter of claim 15 wherein the predistortion circuit is adaptable, and further comprising signal processing circuitry coupled to the predistortion circuit for adapting the predistortion circuit based on at least one of the input signal and the output signal.

23. The transmitter of claim 15 wherein the predistortion circuit is adaptable, and further comprising signal processing circuitry coupled to the predistortion circuit for adapting the predistortion circuit based on at least one of the input signal and a tracking output signal of the power supply.

24. A power amplifier with an envelope-tracking power supply that tracks an envelope of an input signal to the amplifier and varies the level of power supplied to the amplifier in response to variation of the input signal envelope, the amplifier comprising:

a predistortion circuit coupled to the power supply, the predistortion circuit operable for receiving and predistorting the input signal envelope directed to the power supply for addressing the input signal envelope tracking capabilities of the power supply.

25. The power amplifier of claim 24 wherein the predistortion circuit is operable for predistorting the input signal envelope for addressing non-linearities in the envelope tracking of the power supply.

26. The power amplifier of claim 24 wherein the predistortion circuit is a digital predistortion circuit.

27. The power amplifier of claim 24 wherein the predistortion circuit is an analog predistortion circuit.

28. The power amplifier of claim 24 wherein the predistortion circuit is operable for predistorting the input signal envelope to cause over compensation in the level of power supplied to the amplifier by the power supply to ensure proper amplification.

29. The power amplifier of claim 24 wherein the predistortion circuit is adaptable for varying the predistortion of the input signal envelope to maintain proper amplification based on the variation of operational parameters for circuit components of at least one of the amplifier, power supply or predistortion circuit.

30. The power amplifier of claim 24 wherein the predistortion circuit is adaptable, and further comprising signal processing circuitry coupled to the predistortion circuit for adapting the predistortion circuit based on at least one of the input signal and an output signal of the amplifier.

31. The power amplifier of claim 24 wherein the predistortion circuit is adaptable, and further comprising signal processing circuitry coupled to the predistortion circuit for adapting the predistortion circuit based on at least one of the input signal and a tracking output signal of the power supply.

32. The power amplifier of claim 28 wherein the overcompensation caused by the predistortion is related to the level of the input signal envelope.

33. A method of amplifying a signal comprising:

amplifying an input signal with an amplifier to produce an output signal;

tracking the input signal with a power supply coupled to the amplifier and varying the level of power supplied to the amplifier by the power supply in response to variation of the input signal;

predistorting the tracked input signal prior to the power supply for addressing input signal tracking capabilities of the power supply.

34. The method of claim 33 further comprising tracking an input signal envelope, and predistorting the input signal envelope.

35. The method of claim 33 wherein the predistortion of the tracked input signal addresses at least one of non-linearities and slew rate limitations of the power supply.

36. The method of claim 33 further comprising predistorting the input signal with a digital predistortion circuit.

37. The method of claim 33 further comprising predistorting the input signal with an analog predistortion circuit.

38. The method of claim 33 further comprising predistorting the input signal to cause over compensation in the level of power supplied to the amplifier by the power supply to ensure proper amplification.

39. The method of claim 33 further comprising varying the predistortion of the input signal to maintain proper amplification based on the variation of operational parameters for circuit components of at least one of the amplifier, power supply or predistortion circuit.

40. The method of claim 33 further comprising adapting the predistortion of the input signal based on at least one of the input signal and the output signal.

41. The method of claim 33 further comprising adapting the predistortion of the input signal based on at least one of the input signal and an output signal of the power supply.

42. A predistortion circuit for coupling to an envelope-tracking power supply for an amplifier, the predistortion circuit comprising:

a circuit configured to receive a detected envelope of an input signal, the circuit operable for predistorting the input signal envelope and generating an output signal;

the output signal suitable for input to the power supply to affect the power delivered to an amplifier.

43. The predistortion circuit of claim 42 wherein the circuit is operable for predistorting the input signal for addressing at least one of non-linearities and slew rate limitations of the power supply.

44. The predistortion circuit of claim 42 wherein the circuit is a digital predistortion circuit.

45. The predistortion circuit of claim 44 wherein the digital predistortion circuit includes at least one of a Look Up Table circuit or a polynomial-based circuit.

46. The predistortion circuit of claim 42 wherein the circuit is an analog predistortion circuit.

47. The predistortion circuit of claim 42 wherein the analog predistortion circuit includes at least one of a diode, a transistor, or an amplifier.

48. The predistortion circuit of claim 42 wherein the circuit is operable for predistorting the input signal envelope to cause over compensation in the power supplied to the amplifier.

49. The predistortion circuit of claim 42 wherein the circuit is adaptable and further comprising signal processing circuitry coupled to the circuit for adapting the circuit based on at least one of the input signal and an output of an amplifier.

50. The predistortion circuit of claim 42 wherein the circuit is adaptable and further comprising signal processing circuitry coupled to the circuit for adapting the circuit based on at least one of the input signal and an output signal of the power supply.