Method and system to prevent harmonics from causing distortion in a communications system

• US 20090247095A1
• Filed: 03/25/2008
• Published: 10/01/2009
• Est. Priority Date: 03/25/2008
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Pan, Meng-An
• Granted Patent: US 8,639,197 B2
• Time in Patent Office: Days
• US Class Current: 455/115.100
• CPC Class Codes: H04B 17/10 of transmitters

Abstract

According to one exemplary embodiment, a method of preventing harmonics from causing distortion in a communications system includes feeding a test signal through a pre-distortion circuit in the communications system to a transmitter in the communications system. The method continues by transmitting a distorted output signal produced by the transmitter to an analyzer, analyzing the distorted output signal to identify one or more undesired harmonics, and generating and sending calibration data from the analyzer to calibrate the pre-distortion circuit, thereby preventing the one or more undesired harmonics from causing distortion in the communications system. In one embodiment, a system to prevent harmonics from causing distortion in a communications system includes a pre-distortion circuit, a transmitter, and an analyzer configured to identify one or more undesired harmonics and to generate and send calibration data to prevent the undesired harmonics from causing distortion.

Claims

1. A method of preventing harmonics from causing distortion in a communications system, said method comprising:

feeding a test signal through a pre-distortion circuit in said communications system to a transmitter in said communications system;

transmitting a distorted output signal produced by said transmitter to an analyzer;

analyzing said distorted output signal in said analyzer to identify one or more undesired harmonics of said distorted output signal;

generating and sending a calibration data from said analyzer to calibrate said pre-distortion circuit, thereby preventing said one or more undesired harmonics from causing distortion in said communications system.

2. The method of claim 1, wherein said one or more undesired harmonics comprise a third harmonic of said distorted output signal.

3. The method of claim 1, wherein said analyzing comprises determining a third order term coefficient in a power series expansion of a pre-distorted signal.

4. The method of claim 1, wherein said calibration data is determined by respective first and third order term coefficients in a power series expansion of said distorted output signal.

5. The method of claim 1, wherein said one or more undesired harmonics comprise a fifth harmonic of said distorted output signal.

6. The method of claim 1, wherein said analyzing comprises determining respective third and fifth order term coefficients in a power series expansion of a pre-distorted signal.

7. The method of claim 1, wherein said calibration data is determined by respective first, third, and fifth order term coefficients in a power series expansion of said distorted output signal.

8. The method of claim 1, wherein said communications system comprises a transceiver.

9. The method of claim 1, wherein said transmitter is configured to transmit at radio frequency (RF).

10. The method of claim 1, wherein said communications system is selected from the group consisting of a wireless communications device, a mobile telephone, a Bluetooth enabled device, a computer, a satellite set top box, and a personal digital assistant (PDA).

11. A system to prevent harmonics from causing distortion in a communications system, said system comprising:

a pre-distortion circuit configured to receive a test signal from a modulator in said system;

a transmitter configured to receive a signal provided by said pre-distortion circuit;

an analyzer for receiving a distorted output signal produced by said transmitter, said analyzer configured to identify one or more undesired harmonics of said distorted output signal, and further configured to generate and send a calibration data to calibrate said pre-distortion circuit, thereby preventing said one or more undesired harmonics from causing distortion in said communications system.

12. The system of claim 11, wherein said one or more undesired harmonics comprise a third harmonic of said distorted output signal.

13. The system of claim 11, wherein said analyzer is configured to determine a third order term coefficient in a power series expansion of a pre-distorted signal.

14. The system of claim 11, wherein said calibration data is determined by respective first and third order terms coefficient in a power series expansion of said distorted output signal.

15. The system of claim 11, wherein said one or more undesired harmonics comprise a fifth harmonic of said distorted output signal.

16. The system of claim 11, wherein said analyzer is configured to determine respective third and fifth order term coefficients in a power series expansion of a pre-distorted signal.

17. The system of claim 11, wherein said calibration data is determined by respective first, third, and fifth order term coefficients in a power series expansion of said distorted output signal.

18. The system of claim 11, wherein said communications system comprises a transceiver.

19. The system of claim 11, wherein said transmitter is configured to transmit at radio frequency (RF).

20. The system of claim 11, wherein said communications system is selected from the group consisting of a wireless communications device, a mobile telephone, a Bluetooth enabled device, a computer, a satellite set top box, and a personal digital assistant (PDA).