Granted Patent B2

US 6,903,604 · App. 09/876,772 · Granted Jun 7, 2005

Abstract

Claims (107)

1. An apparatus for modeling and estimating the characteristics of a power amplifier, said apparatus comprising:

a predistortion module responsive to an input signal and coefficients of a complex polynomial representative of said amplifier by generating a predistorted signal;

the amplifier responsive to a plurality of time-spaced samples of said predistorted signal by generating an output signal; and

a polynomial module responsive to a current sample of said output signal and to a plurality of time-spaced samples of said predistorted signal by generating an update of said coefficients of a complex polynomial representative of said amplifier as feedback into said predistortion module.

2. The apparatus according to claim 1 , wherein said coefficients are generated for each of a plurality of delay taps.

3. The apparatus according to claim 2 , wherein said polynomial module is represented by the equation

y

n

=

∑

m

=

0

M

-

1

⁢

⁢

B

m

⁢

(

b

m

→

,

x

n

-

m

)

wherein “n” is a time index, wherein x n is a current sample of said predistorted signal, wherein y n is said current sample of said output signal, wherein B m (·) is a polynomial representation of said amplifier, wherein {right arrow over (b)} m is a vector of said complex polynomial coefficients, and wherein M is an order of amplifier memory equal to the number of said plurality of delay taps.

4. The apparatus according to claim 3 , wherein said complex polynomial includes both even and odd terms.

5. The apparatus according to claim 4 , wherein said polynomial module employs a minimum mean squared error criteria to determine said polynomial coefficients.

6. A wireless radio frequency communications system including apparatus for modeling and estimating the characteristics of a power amplifier, said system comprising:

a predistortion module responsive to an input signal and coefficients of a complex polynomial representative of said amplifier by generating a predistorted signal;

the amplifier responsive to a plurality of time-spaced samples of said predistorted signal by generating an output signal; and

a polynomial module responsive to a current sample of said output signal and to a plurality of time-spaced samples of said predistorted signal by generating an update of said coefficients of a complex polynomial representative of said amplifier as feedback into said predistortion module.

7. The system according to claim 6 , wherein said coefficients are generated for each of a plurality of delay taps.

8. The system according to claim 7 , wherein said polynomial module is represented by the equation

y

n

=

∑

m

=

0

M

-

1

⁢

⁢

B

m

⁢

(

b

m

→

,

x

n

-

m

)

wherein “n” is a time index, wherein x n is a current sample of said predistorted signal, wherein y n is said current sample of said output signal, wherein B m (·) is a polynomial representation of said amplifier, wherein {right arrow over (b)} m is a vector of said complex polynomial coefficients, and wherein M is an order of amplifier memory equal to the number of said plurality of delay taps.

9. The system according to claim 8 , wherein said complex polynomial includes both even and odd terms.

10. The system according to claim 9 , wherein said polynomial module employs a minimum mean squared error criteria to determine said polynomial coefficients.

11. A method for modeling and estimating the characteristics of a power amplifier, comprising the steps of:

generating a predistorted signal in response to an input signal and to coefficients of a complex polynomial representative of said amplifier;

amplifying a plurality of time-spaced samples of said predistorted signal to generate an output signal; and

generating an update of said coefficients of a complex polynomial representative of said amplifier in response to a current sample of said output signal and to said plurality of time-spaced samples of said predistorted signal.

12. The method according to claim 11 , wherein said coefficients are generated for each of a plurality of delay taps.

13. The method according to claim 12 , wherein said coefficients generating step is represented by the equation

y

n

=

∑

m

=

0

M

-

1

⁢

⁢

B

m

⁢

(

b

m

→

,

x

n

-

m

)

wherein “n” is a time index, wherein x n is a current sample of said predistorted signal, wherein y n is said current sample of said output signal, wherein B m (·) is a polynomial representation of said amplifier, wherein {right arrow over (b)} m is a vector of said complex polynomial coefficients, and wherein M is an order of amplifier memory equal to the number of said plurality of delay taps.

14. The method according to claim 13 , wherein said complex polynomial includes both even and odd terms.

15. The method according to claim 14 , wherein said coefficients generating step employs a minimum mean squared error criteria to determine said polynomial coefficients.

16. An apparatus for estimating the characteristics of a power amplifier, said apparatus comprising:

a polynomial module responsive to a plurality of time-spaced samples of a predistorted signal by generating a complex polynomial representative for each of said plurality of time-spaced samples;

said polynomial module responsive to a current sample of an output from said amplifier by generating an update for coefficients of said complex polynomial representative of said amplifier.

17. The apparatus according to claim 16 , wherein said polynomial module uses a current sample of said predistorted signal and at least one previous sample of said predistorted signal for characterizing said amplifier.

18. The apparatus according to claim 17 , wherein said amplifier is characterized as a summation of said complex polynomial representatives.

Assignments (9)