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

• US 8,600,305 B2
• Filed: 05/23/2012
• Issued: 12/03/2013
• 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, Afashi, Ali, Magoon, Vikram
• Primary Examiner(s): Alam, Fayyaz
• Assistant Examiner(s): Bilodeau, David
• Application Number:
  US13/478,918
• Publication Number:
  US 20120230375A1
• Time in Patent Office: 559 Days
• Field of Search: 455/63.1
• 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 system implemented in a single chip, comprising:

a radio frequency (RF) receiver;

an RF transmitter, wherein the RF transmitter comprises a power amplifier configured to generate an output signal in response to an input signal;

a feedback mixer circuit configured to perform a frequency mix-down operation on the output signal to generate a feedback signal; and

a plurality of selector switches configured by a baseband processor to insert, during a calibration mode, the generated feedback signal at insertion points in the RF receiver corresponding to in-phase (I) and quadrature-phase (Q) components of the output signal by configuring a closed feedback loop comprising the RF transmitter and a portion of the RF receiver defined by the insertion points.

2. The system of claim 1, wherein the baseband processor is further configured to compensate for at least one of amplitude modulation to amplitude modulation (AM-AM) distortion or amplitude modulation to phase modulation (AM-PM) distortion of the power amplifier utilizing the plurality of selector switches.

3. The system of claim 1, further comprising a signal attenuator configured to attenuate the output signal and transmit the attenuated output signal to the feedback mixer circuit, wherein the signal attenuator is configured to attenuate the output signal based on a linear operating range of the feedback mixer circuit.

4. The system of claim 1, wherein the plurality of selector switches is configured by the baseband processor to disable the closed feedback loop configuration during a normal operating mode.

17. The system of claim 1, wherein the closed feedback loop includes the power amplifier of the RF transmitter.

5. A method, comprising:

in a single chip comprising a dual path radio frequency (RF) receiver and an RF transmitter including a power amplifier,

generating, with the power amplifier, an output signal in response to an input signal;

generating, with a feedback mixer circuit, a feedback signal by performing a frequency mix-down operation on the output signal; and

selectively inserting the feedback signal at a first insertion point and a second insertion point in the dual path RF receiver to characterize performance of the power amplifier, each of the first and second insertion points corresponding to one of the dual paths of the dual path RF receiver, by configuring a closed feedback loop comprising the RF transmitter and a portion of the dual path RF receiver defined by the first insertion point and the second insertion point within the dual path RF receiver.

6. The method of claim 5, wherein generating the feedback signal is performed across distinct power levels of the input signal.

7. The method of claim 6, further comprising estimating an output power level for each generated output signal based on the corresponding feedback signal for each distinct input power level.

8. The method of claim 7, further comprising estimating amplitude distortion in each generated output signal based on:

the estimated output power level and corresponding input power level.

9. The method of claim 6, further comprising estimating an output time instant for each generated output signal in relation to an input time instant for each input signal based on the generated feedback signal for each corresponding distinct input power level.

10. The method of claim 9, further comprising estimating phase distortion in each generated output signal based on:

the estimated output time instant, the input time instant, and the corresponding distinct input signal level.

18. The method of claim 5, wherein the closed feedback loop includes the power amplifier of the RF transmitter.

19. The method of claim 5, wherein the first insertion point corresponds to an in-phase (I) component of the output signal and the second insertion point corresponds to a quadrature-phase (Q) component of the output signal.

11. A system implemented in a single chip, comprising:

a radio frequency (RF) receiver including a first amplifier and a second amplifier;

an RF transmitter, wherein the RF transmitter comprises a power amplifier configured to generate an output signal in response to an input signals;

a feedback mixer circuit configured perform a frequency mix-down operation on the output signal to generate a feedback signal; and

a selection circuit in the RF receiver configured to insert the generated feedback signal at insertion a first insertion point and a second insertion point in the RF receiver by configuring a closed feedback loop comprising the RF transmitter and a portion of the RF receiver defined by the insertion points, wherein the first insertion point corresponds to an input of the first amplifier and the second insertion point corresponds to an input of the second amplifier.

12. The system of claim 11, wherein a signal attenuator is configured to attenuate the output signal based on a linear operating range of the feedback mixer circuit.

13. The system of claim 11, wherein the feedback mixer circuit is configured to generate feedback signals for corresponding distinct power levels of the input signal, and further comprising a baseband processor configured to estimate an output power level for each generated output signal based on the generated feedback signal for each corresponding distinct input power level.

14. The system of claim 13, wherein the baseband processor is further configured to estimate amplitude distortion in each generated output signal based on:

the estimated output power level and corresponding input power level.

15. The system of claim 14, wherein the baseband processor is further configured to estimate an output time instant for each generated output signal in relation to an input time instant for each input signal based on the generated feedback signal for each corresponding distinct input power level.

16. The system of claim 15, wherein the baseband processor is further configured to estimate phase distortion in each generated output signal based on:

the estimated output time instant, the input time instant, and the corresponding distinct input signal level.

20. The system of claim 11, wherein the RF receiver includes a first path and a second path, and the insertion points include the first insertion point and the second insertion point, and each of the insertion points corresponds to one of the paths of the RF receiver.