SYSTEM AND A METHOD FOR SIGNAL PROCESSING

• US 20110006842A1
• Filed: 07/08/2009
• Published: 01/13/2011
• Est. Priority Date: 07/08/2009
• Status: Active Grant

• Current Assignee: Doron Shahar Koren, Sergey Toujikov
• Original Assignee: Doron Shahar Koren, Sergey Toujikov
• Inventors: KOREN, Doron Shahar, Toujikov, Sergey
• Granted Patent: US 7,948,310 B2
• Time in Patent Office: Days
• US Class Current: 330/185
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 2201/3233 Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion

Abstract

A system for processing an input signal, the system including: (a) a hardware memory module configured to store a lookup table; and (b) a signal processing module, configured to process the input signal to provide a second signal, and to transmit the second signal to a power amplifier that is characterized by non-linearity and which is adapted to amplify the second signal to provide an amplified signal; wherein the signal processing module is configured to process the input signal in response to at least one filtering parameter to provide the second signal so as to at least partly compensate for the non-linearity of the amplifier; wherein the at least one filtering parameter is retrieved from the lookup table using a first, a second, and a third lookup table indexes, wherein the first index is responsive to a magnitude of the input signal at a first moment, the second index is responsive to a magnitude of the input signal at a second moment, and the third index is responsive to phases of the input signal at the first and the second moments.

Claims

1. A system for processing an input signal, the system comprising:

a hardware memory module configured to store a lookup table; and

a signal processing module, configured to process the input signal to provide a second signal, and to transmit the second signal to a power amplifier that is characterized by non-linearity and which is adapted to amplify the second signal to provide an amplified signal;

wherein the signal processing module is configured to process the input signal in response to at least one filtering parameter to provide the second signal so as to at least partly compensate for the non-linearity of the amplifier;

wherein the at least one filtering parameter is retrieved from the lookup table using a first, a second, and a third lookup table indexes, wherein the first index is responsive to a magnitude of the input signal at a first moment, the second index is responsive to a magnitude of the input signal at a second moment, and the third index is responsive to phases of the input signal at the first and the second moments.

2. The system according to claim 1, further comprising the power amplifier that is characterized by the non-linearity, and that is adapted to amplify the second signal to provide the amplified signal.

3. The system according to claim 1, wherein the at least one filtering parameter consists of a complex compensation coefficient, wherein the signal processing module is configured to multiply the input signal by the compensation coefficient.

4. The system according to claim 1, wherein the memory module is configured to store a three dimensional lookup table.

5. The system according to claim 1, further comprising a table updating module, configured to update at least one filtering parameter of the lookup table in response to the amplified signal.

6. The system according to claim 1, further comprising a table updating module, configured to update the lookup table in response to a physical condition of the power amplifier.

7. The system according to claim 1, wherein the signal processing module is further configured to determine in response to the input signal whether to process the input signal, wherein the signal processing module is further configured to selectively process the input signal in response to a result of the determining.

8. The system according to claim 1, further comprising a table updating module, configured to write to the lookup table at least one filtering parameter that is determined by minimizing a difference between a signal processed using the lookup table and a signal processed using another filter.

9. The system according to claim 1, wherein the first and the second moments are consecutive moments of a discrete sampling scheme.

10. The system according to claim 1, wherein the third index is responsive to a difference between the phases of the input signal at the first and the second moments.

11. The system according to claim 1, wherein the signal processing module is configured to process the input signal in response to at least one interpolated value that is determined in response to at least one filtering parameter and to at least one other filtering parameter, wherein the at least one other filtering parameter is retrieved from the lookup table using at least one lookup table index that is different from the first, the second, and the third lookup table indexes, and which is responsive to a parameter selected from a list consisting of the magnitude of the input signal at the first moment, the magnitude of the input signal at the second moment, and the phases of the input signal at the first and the second moments.

12. A method for processing an input signal, the method comprising:

retrieving from a lookup table at least one filtering parameter using a first, a second, and a third lookup table indexes, wherein the first index is responsive to a magnitude of the input signal at a first moment, the second index is responsive to a magnitude of the input signal at a second moment, and the third index is responsive to phases of the input signal at the first and the second moments;

processing the input signal in response to the at least one filtering parameter, to provide a second signal; and

transmitting the second signal to a power amplifier that is characterized by non-linearity and which is adapted to amplify the second signal to provide an amplified signal;

wherein the processing comprises processing the input signal to provide the second signal so as to at least partly compensate for the non-linearity of the amplifier.

13. The method according to claim 12, further comprising amplifying the second signal by the power amplifier to provide the amplified signal.

14. The method according to claim 12, wherein the at least one filtering parameter consists of a complex compensation coefficient, wherein the processing comprises multiplying the input signal by the compensation coefficient.

15. The method according to claim 12, wherein the retrieving comprises retrieving the at least one filtering parameter from a three dimensional lookup table.

16. The method according to claim 12, further comprising updating at least one filtering parameter of the lookup table in response to the amplified signal.

17. The method according to claim 12, wherein the retrieving comprises retrieving the at least one filtering parameter from the lookup table that is implemented by hardware.

18. The method according to claim 12, further comprising updating the lookup table in response to a physical condition of the power amplifier.

19. The method according to claim 12, wherein the processing is preceded by determining in response to the input signal whether to process the input signal, wherein the processing is selectively carried out in response to a result of the determining.

20. The method according to claim 12, wherein the retrieving is preceded by determining at least one filtering parameter of the lookup table by minimizing a difference between a signal processed using the lookup table and a signal processed using another filter.

21. The method according to claim 12, wherein the first and the second moments are consecutive moments of a discrete sampling scheme.

22. The method according to claim 12, wherein the third index is responsive to a difference between the phases of the input signal at the first and the second moments.

23. The method according to claim 12, further comprising retrieving from the lookup table at least one other filtering parameter using at least one lookup table index that is different from the first, the second, and the third lookup table indexes, and which is responsive to a parameter selected from a list consisting of the magnitude of the input signal at the first moment, the magnitude of the input signal at the second moment, and the phases of the input signal at the first and the second moments;

wherein the processing is responsive to at least one interpolated value that is determined in response to at least one filtering parameter and to at least one other filtering parameter.