Linear equalizers for outphasing amplification

Patent metadata

Field	Value
Publication number	US-10103908-B1
Application number	US-201715593712-A
Country	US
Kind code	B1
Filing date	May 12, 2017
Priority date	May 12, 2016
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Embodiments are directed to an apparatus, method and system for relative or absolute equalization of two or more channels. The apparatus includes a receiver that receives a variable-envelope signal, a self-consistent outphasing separator that splits the received variable-envelope signal into constant-envelope signals, and linear pre-equalizers that equalize the constant-envelope signals relative to each other or to some target. The apparatus also includes an analog combiner that combines the constant-envelope signals, and a feedback loop with a processor that receives the combined constant-envelope signals as inputs, analyzes the combined constant-envelope signals to identify pre-equalization inputs that, when applied to the linear pre-equalizers, will equalize the constant-envelope signals, and provide the identified pre-equalization inputs to the linear pre-equalizers, so that the combined constant-envelope signals are equalized relative to each other or to some target. Adaptive algorithms use a dedicated calibration signal, regularly transmitted (data) signal or combination of the two.

First claim

We claim:

1. An apparatus for relative or absolute equalization of two or more channels, the apparatus comprising:
a receiver configured to receive a variable-envelope signal;
an outphasing separator configured to split the received variable-envelope signal into first and second constant-envelope signals;
a first linear pre-equalizer configured to equalize the first constant-envelope signal relative to the second constant-envelope signal and provide a first pre-equalized constant-envelope signal;
a second linear pre-equalizer configured to equalize the second constant-envelope signal relative to the first constant-envelope signal and provide a second pre-equalized constant-envelope signal;
an analog combiner configured to combine the first and second pre-equalized constant-envelope signals; and
a feedback loop comprising at least one processor configured to:
receive the combined first and second pre-equalized constant-envelope signals as inputs;
analyze the received combined first and second pre-equalized constant-envelope signals to identify one or more pre-equalization inputs that, when applied to the first and/or the second linear pre-equalizers, equalize the first and/or second pre-equalized constant-envelope signals relative to each other; and
provide the identified pre-equalization inputs to the first and/or the second linear pre-equalizers, such that the combined first and second pre-equalized constant-envelope signals are equalized relative to each other.

2. The apparatus of claim 1 , further comprising:
a first analog component chain comprising one or more analog electrical components configured to receive and process the first constant-envelope signal; and
a second analog component chain comprising one or more analog electrical components configured to receive and process the second constant-envelope signal.

3. The apparatus of claim 2 , wherein the pre-equalization inputs resolve physical component-based differences in the first and second analog component chains including the analog combiner.

4. The apparatus of claim 2 , wherein the first and second linear pre-equalizers are each individually adjusted such that upon receiving the combined first and second constant-envelope signals at the end of the first and second analog component chains, the pre-equalizer adjustments compensate for relative signal differences between the first and second constant-envelope signals.

5. The apparatus of claim 1 , wherein the variable-envelope signal comprises a two-tone signal.

6. The apparatus of claim 5 , wherein the first and second linear pre-equalizers are adjusted according to feedback based on the two-tone signal, and further based on knowledge of the variable-envelope signal and adaptive algorithm.

7. The apparatus of claim 6 , wherein data is transmitted in a data signal using the apparatus, upon completion of the adjusting using the two-tone signal.

8. The apparatus of claim 7 , wherein at least one of the first or the second pre-equalizers are continually adjusted using the data signal.

9. The apparatus of claim 5 , wherein the first and second linear pre-equalizers are adjusted to a common flat target determined for each analog component chain.

10. A method for performing a fundamental optimization function using an adaptive algorithm to minimize distortions as measured at an output of a combiner, the method including:
receiving a combined pre-equalized constant-envelope signal that was combined by an analog combiner that received two separate, pre-equalized first and second constant-envelope signals as inputs;
analyzing the received combined pre-equalized constant-envelope signal to identify one or more pre-equalization inputs which, when applied at first and second linear pre-equalizers, equalize first and second constant-envelope signals relative to each other; and
providing the one or more identified pre-equalization inputs to the first and the second linear pre-equalizers, such that in the combined pre-equalized constant-envelope signal, the first and second constant-envelope signals are equalized relative to each other.

11. The method of claim 10 , wherein the first and second constant-envelope signals are frequency agnostic.

12. The method of claim 10 , wherein the first and second constant-envelope signals are modulation agnostic.

13. The method of claim 10 , wherein the first and second constant-envelope signals are separated using an outphasing separator which performs self-consistent outphasing signal separation.

14. The method of claim 13 , wherein the outphasing separator and the first and second linear pre-equalizers support a specified portion of an overall expanded frequency spectrum that is supported at a given point in time.

15. A system configured to provide relative or absolute equalization of two or more RF channels, the apparatus comprising:
a receiver configured to receive a variable-envelope signal;
an outphasing separator configured to split the received variable-envelope signal into first and second constant-envelope signals;
a first linear pre-equalizer configured to equalize the first constant-envelope signal relative to the second constant-envelope signal and provide a first pre-equalized constant-envelope signal;
a second linear pre-equalizer configured to equalize the second constant-envelope signal relative to the first constant-envelope signal and provide a second pre-equalized constant-envelope signal;
an analog combiner configured to combine the first and second pre-equalized constant-envelope signals; and
a feedback loop comprising at least one processor configured to:
receive the combined first and second pre-equalized constant-envelope signals as inputs;
analyze the received combined first and second pre-equalized constant-envelope signals in conjunction with a known transmitted variable-envelope signal to identify one or more pre-equalization inputs that, when applied to the first and/or the second linear pre-equalizers, equalize the first and/or second constant-envelope signals relative to each other; and
provide the identified pre-equalization inputs to the first and/or the second linear pre-equalizers, such that the combined first and second pre-equalized constant-envelope signals are equalized relative to each other or to some known absolute target.

16. The system of claim 15 , wherein the feedback loop comprises a temporary feedback loop that is initially established at calibration and is subsequently circumvented.

17. The system of claim 15 , wherein calibration tables or equations are built that provide one or more inputs regarding operating characteristics of the analog components.

18. The system of claim 17 , wherein the calibration, using the calibration tables, is performed by scanning over an expanded frequency spectrum and/or over temperature, signal power or other specified variables.

19. The system of claim 15 , wherein the feedback loop comprises a substantially permanent feedback loop that is integrated into the system using one or more hardware components and/or one or more software components.

20. The system of claim 19 , wherein a specified calibration signal and/or a regularly transmitted, data-carrying signal is used for adapting the pre-equalization inputs over time.

Assignees

• L3 Tech Inc

Inventors

• Jeraj Janez
• Harris Johnny M
• Landon David G
• Mcintire William K

Classifications

• H04L2025/03783

  Details of reference signals · CPC title

• H04L2025/03681

  Control of adaptation · CPC title

• H04L25/03057 Primary

  with a recursive structure (H04L25/03031 takes precedence) · CPC title

• H04L25/03343

  Arrangements at the transmitter end · CPC title