Method of correcting distortion in a power amplifier

• US 20040142667A1
• Filed: 01/21/2003
• Published: 07/22/2004
• Est. Priority Date: 01/21/2003
• Status: Abandoned Application

• Current Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Original Assignee: Nokia Solutions and Networks US LLC (Nokia Corporation)
• Inventors: Lochhead, Donald Laird, Bramble, Robert Alan, Andrews, Michael Scott
• Application Number:
  US10/347,428
• Publication Number:
  US 20040142667A1
• Time in Patent Office: Days
• US Class Current: 455/114.3
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3294 Acting on the real and imaginary components of the input signal
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 2201/3233 Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence

Abstract

The invention is a method of correcting distortion in a power amplifier in a transmitter. The method includes applying an input time varying modulated data signal to the power amplifier which outputs an amplified time varying modulated data signal which is an amplification of the input time varying modulated data signal; storing samples of the input time varying modulated data signal; storing samples of the output amplified time varying data signal; using the stored input and output time varying modulated samples to provide a processor implemented model with parameters representing a non-linear characteristic of the power amplifier without the use of any polynomials; and producing predistortion coefficients.

Claims

1. A method of correcting distortion in a power amplifier in a transmitter comprising:

(a) applying an input time varying modulated data signal to the power amplifier which outputs an amplified time varying modulated data signal which is an amplification of the input time varying modulated data signal;

(b) storing samples of the input time varying modulated data signal;

(c) storing samples of the output amplified time varying data signal;

(d) using the stored input and output time varying modulated samples to provide a processor implemented model with parameters representing a non-linear characteristic of the power amplifier without the use of any polynomials; and

(e) in response to the non-linear characteristic producing predistortion coefficients which are applied to a data signal which is input to the power amplifier and amplified by the power amplifier to correct distortion in an amplification of the data signal which is an output of the power amplifier.

2. A method in accordance with claim 1 wherein:

the non-linear characteristic is expressed by an equation of a form y=m×

+b+c wherein

y is the output signal of the power amplifier;

x is the input signal;

m is a constant; and

c is a non-linear function of x including logarithms.

3. A method in accordance with claim 2 wherein:

the logarithms include a number base raised to a first power of x and additional terms.

4. A method in accordance with claim 3 wherein:

the number base is 10.

5. A method in accordance with claim 3 wherein:

the number base is 2.

6. A method in accordance with claim 1 wherein:

the non-linear characteristic is a gain and a phase characteristic of the power amplifier.

7. A method in accordance with claim 6 wherein the gain characteristic comprises:

a voltage or a current gain of the power amplifier.

8. A method in accordance with claim 1 wherein:

the non-linear characteristic is a temperature characteristic of the power amplifier.

9. A method in accordance with claim 1 wherein:

the non-linear characteristic is a frequency characteristic of the power amplifier.

10. A method in accordance with claim 2 wherein:

the non-linear characteristic is a gain and a phase characteristic of the power amplifier.

11. A method in accordance with claim 2 wherein the gain characteristic comprises:

a voltage or a current gain of the power amplifier.

12. A method in accordance with claim 2 wherein:

the non-linear characteristic is a temperature characteristic of the power amplifier.

13. A method in accordance with claim 2 wherein:

the non-linear characteristic is a frequency characteristic of the power amplifier.

14. A method in accordance with claim 3 wherein:

the non-linear characteristic is a gain and a phase characteristic of the power amplifier.

15. A method in accordance with claim 3 wherein the gain characteristic comprises:

a voltage or a current gain.

16. A method in accordance with claim 3 wherein:

the non-linear characteristic is a temperature characteristic of the power amplifier.

17. A method in accordance with claim 3 wherein:

the non-linear characteristic is a frequency characteristic of the power amplifier.

18. A method in accordance with claim 4 wherein:

the non-linear characteristic is a gain and a phase characteristic of the power amplifier.

19. A method in accordance with claim 4 wherein the gain characteristic comprises:

a voltage or a current gain.

20. A method in accordance with claim 4 wherein:

the non-linear characteristic is a temperature characteristic of the power amplifier.

21. A method in accordance with claim 4 wherein:

the non-linear characteristic is a frequency characteristic of the power amplifier.

22. A method in accordance with claim 5 wherein:

the non-linear characteristic is a gain and a phase characteristic of the power amplifier.

23. A method in accordance with claim 5 wherein the gain characteristic comprises:

a voltage or a current gain.

24. A method in accordance with claim 5 wherein:

the non-linear characteristic is a temperature characteristic of the power amplifier.

25. A method in accordance with claim 5 wherein:

the non-linear characteristic is a frequency characteristic of the power amplifier.

26. In a mobile RF device including a power amplifier, a method of correcting distortion in the power amplifier comprising:

(a) applying an input time varying modulated data signal to the power amplifier which outputs an amplified time varying modulated data signal which is an amplification of the input time varying modulated data signal;

(b) storing samples of the input time varying modulated data signal;

(c) storing samples of the output amplified time varying data signal;

(d) using the stored input and output time varying modulated samples to provide a processor implemented model with parameters representing a non-linear characteristic of the power amplifier without the use of any polynomials; and

(e) in response to the non-linear characteristic producing predistortion coefficients which are applied to a data signal which is input to the power amplifier and amplified by the power amplifier to correct distortion in an amplification of the data signal which is an output of the power amplifier.

27. A method in accordance with claim 26 comprising:

the non-linear characteristic is expressed by an equation of a form y=m×

+b+c wherein

y is the output signal of the power amplifier;

x is the input signal;

m is a constant; and

c is a non-linear function of x including logarithms.

28. A method in accordance with claim 27 comprising:

the logarithms include a number base raised to a first power of x and additional terms.

29. A method in accordance with claim 27 comprising:

the number base is 10.

30. A method in accordance with claim 26 comprising:

the number base is 2.

31. A method in accordance with claim 26 comprising:

the non-linear characteristic is a gain and a phase characteristic of the power amplifier.

32. In a base station including a power amplifier, a method of correcting distortion in the power amplifier comprising:

(a) applying an input time varying modulated data signal to the power amplifier which outputs an amplified time varying modulated data signal which is an amplification of the input time varying modulated data signal;

(b) storing samples of the input time varying modulated data signal;

(c) storing samples of the output amplified time varying data signal;

(d) using the stored input and output time varying modulated samples to provide a processor implemented model with parameters representing a non-linear characteristic of the power amplifier without the use of any polynomials; and

(e) in response to the non-linear characteristic producing predistortion coefficients which are applied to a data signal which is input to the power amplifier and amplified by the power amplifier to correct distortion in an amplification of the data signal which is an output of the power amplifier.

33. A method in accordance with claim 32 comprising:

the non-linear characteristic is expressed by an equation of a form y=m×

+b+c wherein

y is the output signal of the power amplifier;

x is the input signal;

m is a constant; and

c is a non-linear function of x including logarithms.

34. A method in accordance with claim 33 comprising:

the logarithms include a number base raised to a first power of x and additional terms.

35. A method in accordance with claim 34 comprising:

the number base is 10.

36. A method in accordance with claim 34 comprising:

the number base is 2.

37. A method in accordance with claim 32 comprising:

the non-linear characteristic is a gain and a phase characteristic of the power amplifier.

38. In a mobile RF device including a power amplifier, a method of correcting distortion in a power amplifier comprising:

(a) applying an input time varying modulated data signal to the power amplifier which outputs an amplified time varying modulated data signal which is an amplification of the input time varying modulated data signal;

(b) storing samples of the input time varying modulated data signal;

(c) storing samples of the output amplified time varying data signal;

(d) using the stored input and output time varying modulated samples to provide a processor implemented model with parameters representing a non-linear characteristic of the power amplifier without the use of any polynomials; and

(f) in response to the non-linear characteristic producing predistortion coefficients which are applied to a data signal which is input to the power amplifier and amplified by the power amplifier to correct distortion in an amplification of the data signal which is an output of the power amplifier.

39. A method in accordance with claim 38 comprising:

the non-linear characteristic is expressed by an equation of a form y=m×

+b+c wherein

y is the output signal of the power amplifier;

x is the input signal;

m is a constant; and

c is a non-linear function of x including logarithms.

40. A method in accordance with claim 39 comprising:

the logarithms include a number base raised to a first power of x and additional terms.

41. A method in accordance with claim 40 comprising:

the number base is 10.

42. A method in accordance with claim 40 comprising:

the number base is 2.