Method and system for compensating for estimated distortion in a transmitter by utilizing a digital predistortion scheme with a single feedback mixer

• US 8,224,250 B2
• Filed: 12/29/2006
• Issued: 07/17/2012
• Est. Priority Date: 12/06/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Behzad, Arya, Afsahi, Ali, Magoon, Vikram
• Primary Examiner(s): Ghebretinsae, Temesgh
• Assistant Examiner(s): Bilodeau, David
• Application Number:
  US11/618,699
• Publication Number:
  US 20080137772A1
• Time in Patent Office: 2,027 Days
• Field of Search: 455/63.1, 455/119.3, 375/296, 375/285
• US Class Current: 455/63.1
• 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 2200/57 Separate feedback of real and complex signals being present
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

Aspects of a method and system for compensating for estimated distortion in a transmitter by utilizing a digital predistortion scheme with a single feedback mixer are presented. Aspects of the system may include at least one circuit that enables generation of an output signal in response to one or more generated input signals. A feedback signal may be generated within a single feedback mixer circuit that may perform a frequency mix-down operation on the generated output signal. The generated feedback signal may be inserted at one or more insertion points in a receiver. Each of the insertion points may be located between a mixer stage of the receiver, and one or more circuits that generate a baseband signal based on the generated feedback signal.

Claims

1. A method for calibrating a transmitter circuit in a wireless communications system, the method comprising:

in a single chip comprising a radio frequency (RF) transmitter and an RF receiver, generating an output signal at an output of one or more power amplifiers in said RF transmitter in response to one or more generated input signals;

generating within a single feedback mixer circuit in said single chip, a feedback signal by performing a frequency mix-down operation on said generated output signal; and

selectively inserting said generated feedback signal at one or more insertion points in said RF receiver utilizing one or more switches according to one of a normal operating mode and a calibration mode, wherein each of said one or more insertion points is located between a mixer stage of said RF receiver and one or more circuits within said single chip that generate a baseband signal based on said generated feedback signal, and wherein said mixer stage of said RF receiver is separate from said single feedback mixer circuit, and wherein selectively inserting according to said calibration mode comprises configuring a closed feedback loop comprising said RF transmitter and a portion of said RF receiver defined by said one or more insertion points.

2. The method according to claim 1, comprising performing said frequency mix-down operation on an attenuated version of said generated output signal.

3. The method according to claim 2, compris1ng selecting an attenuation level for generating said attenuated version of said generated output signal.

4. The method according to claim 1, comprising configuring said RF receiver for said insertion of said generated feedback signal.

5. The method according to claim 1, comprising selecting a frequency for said frequency mix-down operation.

6. The method according to claim 5, wherein said selected frequency is a local oscillator frequency utilized by said single feedback mixer circuit.

7. The method according to claim 1, comprising generating a plurality of said one or more input signals and receiving a corresponding plurality of said one or more generated baseband signals.

8. The method according to claim 7, wherein each of said generated plurality of said one or more input signals comprises a corresponding one or more distinct input power level.

9. The method according to claim 8, comprising estimating an output power level for said generated output signal based on said generated feedback signal for each of said corresponding one or more distinct input power level.

10. The method according to claim 9, comprising estimating amplitude distortion in said generated output signal based on said estimated output power level and one or more of said distinct input power level.

11. The method according to claim 8, comprising estimating an output time instant for said generated output signal in relation to an input time instant for said generated at least one input signal based on said generated feedback signal for each said corresponding one or more distinct input power level.

12. The method according to claim 11, comprising estimating phase distortion in said generated output signal based on said estimated output time instant, said input time instant and at least one of said corresponding one or more distinct input signal level.

25. The method according to claim 1, wherein said one or more circuits within said single chip that generate said baseband signal comprise a baseband processor.

27. The method according to claim 1, comprising configuring one or more switches in said RF receiver for said insertion of said generated feedback signal.

13. A system for calibrating a transmitter circuit in a wireless communications system, the system comprising:

at least one circuit in a single chip comprising a radio frequency (RF) transmitter and an RF receiver, said at least one circuit enables generation of an output signal at an output of one or more power amplifiers in said RF transmitter in response to one or more generated input signals;

said at least one circuit enables generation, within a single feedback mixer circuit in said single chip, of a feedback signal by performing a frequency mix-down operation on said generated output signal; and

said at least one circuit enables selective insertion of said generated feedback signal at one or more insertion points in said RF receiver utilizing one or more switches according to one of a normal operating mode and a calibration mode, wherein each of said one or more insertion points is located between a mixer stage of said RF receiver and one or more circuits within said single chip that generate a baseband signal based on said generated feedback signal, wherein said mixer stage of said RF receiver is separate from said single feedback mixer circuit, and wherein during calibration mode, said one or more circuits for generating said baseband signal is further configured to compensate for at least one of AM-AM distortion and AM-PM distortion of said one or more power amplifiers.

14. The system according to claim 13, wherein said at least one circuit enables performance of said frequency mix-down operation on an attenuated version of said generated output signal.

15. The system according to claim 14, wherein said at least one circuit enables selection of an attenuation level for generating said attenuated version of said generated output signal.

16. The system according to claim 13, wherein said at least one circuit enables configuration of said RF receiver for said insertion of said generated feedback signal.

17. The system according to claim 13, wherein said at least one circuit enables selection of a frequency for said frequency mix-down operation.

18. The system according to claim 17, wherein said selected frequency is a local oscillator frequency utilized by said single feedback mixer circuit.

19. The system according to claim 13, wherein said at least one circuit enables generation of a plurality of said one or more input signals and reception of a corresponding plurality of said one or more generated baseband signals.

20. The system according to claim 19, wherein each of said generated plurality of said one or more input signals comprises a corresponding one or more distinct input power level.

21. The system according to claim 20, wherein said at least one circuit enables estimation of an output power level for said generated output signal based on said generated feedback signal for each of said corresponding one or more distinct input power level.

22. The system according to claim 21, wherein said at least one circuit enables estimation of amplitude distortion in said generated output signal based on said estimated output power level and one or more of said distinct input power level.

23. The system according to claim 20, wherein said at least one circuit enables estimation of an output time instant for said generated output signal in relation to an input time instant for said generated at least one input signal based on said generated feedback signal for each said corresponding one or more distinct input power level.

24. The system according to claim 23, wherein said at least one circuit enables estimation of phase distortion in said generated output signal based on said estimated output time instant, said input time instant and at least one of said corresponding one or more distinct input signal level.

26. The system according to claim 13, wherein said one or more circuits within said single chip that generate said baseband signal comprise a baseband processor.

28. The system according to claim 13, wherein said at least one circuit enables configuration of one or more switches in said RF receiver for said insertion of said generated feedback signal.

29. A system for calibrating a transmitter circuit, the system comprising:

means for generating an output signal at an output of one or more power amplifiers in a radio frequency (RF) transmitter in response to one or more generated input signals;

means for generating a feedback signal by performing a frequency mix-down operation on the generated output signal; and

means for selectively inserting the generated feedback signal at one or more insertion points in an RF receiver utilizing one or more switches according to one of a normal operating mode and a calibration mode, wherein each of the one or more insertion points is located between a mixer stage of the RF receiver and one or more circuits that generate a baseband signal based on the generated feedback signal, and wherein in calibration mode, the inserting means configures a closed feedback loop comprising the RF transmitter and a portion of the RF receiver defined by the one or more insertion points.