WEIGHTED MEMORY POLYNOMIAL METHOD AND SYSTEM FOR POWER AMPLIFIERS PREDISTORTION

• US 20170047899A1
• Filed: 09/30/2016
• Published: 02/16/2017
• Est. Priority Date: 11/05/2014
• Status: Active Grant

• Current Assignee: King Fahd University Of Petroleum And Minerals
• Original Assignee: King Fahd University Of Petroleum And Minerals
• Inventors: ABDELRAHMAN, Abdalla Ebrahim, HAMMI, Oualid, ZERGUINE, Azzedine
• Granted Patent: US 9,660,593 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/3258 based on polynomial terms
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2201/3224 Predistortion being done for compensating memory effects
• CPC Class Codes: H03F 2201/3231 Adaptive predistortion using phase feedback from the output of the main amplifier
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/21 with semiconductor devices only H03F3/245 takes precedence
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 2001/0425 with linearisation using predistortion

Abstract

A system and method for linearizing a power amplifier using digital predistortion technique is provided including processing circuitry, the processing circuitry configured to apply a digital predistortion function based on a weighted static polynomial function, a weighted dynamic polynomial function and a threshold parameter which splits the nonlinear transfer characteristics of the device under test into a region where the static nonlinearity predominates and a region where the dynamic distortions predominate.

Claims

1. A system for linearizing a power amplifier through digital predistortion, comprising processing circuitry configured to:

obtain an input signal sample that depends on an input signal to the power amplifier;

predistort the input signal sample using a static weight function to generate a first intermediate predistorted signal sample;

predistort the same input signal sample using a dynamic weight function to generate a second intermediate predistorted signal sample;

combine additively the first intermediate predistorted signal sample and the second intermediate predistorted signal sample together to obtain an output signal sample of the predistorter.

2. The system of claim 1, wherein the processing circuitry is further configured to determine the output signal sample of the predistorter using:

3. The system of claim 2, wherein the processing circuitry further configured to determine the static weight polynomial function using:

4. The system of claim 3, wherein the function F(i) is defined according to:

F(i)=i

wherein i is a nonlinearity order.

5. The system of claim 2, wherein the processing circuitry further configured to determine the dynamic weight function using:

6. The system of claim 5, wherein the function G(i,j) is defined according to:

7. The system of claim 2, wherein the threshold parameter |x|_th splits the nonlinear transfer characteristics of the device under test into a region where the static nonlinearity predominates and a region where the dynamic distortions predominate.

8. A method for linearizing a power amplifier through digital predistortion, comprising:

obtaining, with processing circuitry, an input signal sample that depends on an input signal to the power amplifier;

predistorting, with processing circuitry, the input signal sample using a static weight function to generate a first intermediate predistorted signal sample;

predistorting, with processing circuitry, the same input signal sample using a dynamic weight function to generate a second intermediate predistorted signal sample;

combining, with processing circuitry, additively the first intermediate predistorted signal sample and the second intermediate predistorted signal sample together to obtain an output signal sample of the predistorter.

9. The method of claim 8, wherein the processing circuitry is further configured to determine the predistortion function using:

10. The system of claim 8, wherein the processing circuitry further configured to determine the static weight function using:

11. The method of claim 10, wherein the function F(i) is defined according to:

F(i)=i

wherein i is a nonlinearity order.

12. The method of claim 8, wherein the processing circuitry further configured to determine the dynamic weight function using:

13. The method of claim 12, wherein the function G(i,j) is defined according to:

14. The method of claim 8, wherein the threshold parameter |x|_th splits the nonlinear transfer characteristics of the device under test into a region where the static nonlinearity predominates and a region where the dynamic distortions predominate.