LINEARIZATION OF INTERMODULATION BANDS FOR CONCURRENT DUAL-BAND POWER AMPLIFIERS

• US 20150049841A1
• Filed: 12/02/2013
• Published: 02/19/2015
• Est. Priority Date: 05/22/2013
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Laporte, Pierre-Andre, Rollins, Mark Edward, Cao, Haiying
• Granted Patent: US 9,385,762 B2
• Time in Patent Office: Days
• US Class Current: 375/297
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 1/34 Negative-feedback-circuit arrangements with or without positive feedback H03F1/02 - H03F1/30, H03F1/38 - H03F1/50, H03F3/50 take precedence ; for rejection of common mode signals H03F3/45479
• CPC Class Codes: H03F 2200/111 the amplifier being a dual or triple band amplifier, e.g. 900 and 1800 MHz, e.g. switched or not switched, simultaneously or not
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H04B 1/0053 with common antenna for more than one band
• CPC Class Codes: H04B 1/0067 with one or more circuit blocks in common for different bands
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 1/0483 Transmitters with multiple parallel paths
• CPC Class Codes: H04B 1/62 for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
• CPC Class Codes: H04B 2001/0425 with linearisation using predistortion
• CPC Class Codes: H04B 2001/0433 with linearisation using feedback

Abstract

Systems and methods are disclosed for digital predistortion for a concurrent multi-band transmitter that compensates for both in-band and out-of-band intermodulation products according to a memory polynomial based baseband model. In one embodiment, a concurrent multi-band transmitter includes a digital predistortion subsystem, power amplifier circuitry, and an adaptation subsystem. The digital predistortion subsystem includes multiple digital predistorters configured to process digital input signals for frequency bands of a concurrent multi-band signal to provide predistorted digital input signals each being for a different one of the frequency bands of the concurrent multi-band signal and one or more intermodulation distortion compensation signals each being for a different one of one or more intermodulation distortion frequency bands. The adaptation subsystem is configured to adaptively configure the plurality of digital predistorters according to a memory polynomial based digital baseband model of the digital predistorters.

Claims

1. A concurrent multi-band transmitter, comprising:

a digital predistortion subsystem comprising a plurality of digital predistorters configured to process a plurality of digital input signals for a plurality of frequency bands of a concurrent multi-band signal to provide a plurality of predistorted digital input signals each being for a different one of the plurality of frequency bands of the concurrent multi-band signal and one or more intermodulation distortion compensation signals each being for a different one of one or more intermodulation distortion frequency bands;

circuitry configured to process the plurality of predistorted digital input signals and the one or more intermodulation distortion compensation signals to provide a predistorted concurrent multi-band signal;

power amplifier circuitry configured to amplify the predistorted concurrent multi-band signal to provide the concurrent multi-band signal; and

an adaptation subsystem configured to adaptively configure the plurality of digital predistorters based on a memory polynomial based digital baseband model of the plurality of digital predistorters.

2. The transmitter of claim 1 wherein the one or more intermodulation distortion frequency bands comprise a plurality of intermodulation distortion frequency bands such that the one or more intermodulation distortion compensation signals comprise a plurality of intermodulation distortion compensation signals each being for a different one of the plurality of intermodulation distortion frequency bands, and the plurality of digital predistorters comprise:

a first plurality of digital predistorters comprising a separate digital predistorter for each of the plurality of frequency bands of the concurrent multi-band signal, the first plurality of digital predistorters configured to process the plurality of digital input signals to provide the plurality of predistorted digital input signals; and

a second plurality of digital predistorters comprising a separate digital predistorter for each of the plurality of intermodulation distortion frequency bands, the second plurality of digital predistorters configured to process the plurality of digital input signals to provide the plurality of intermodulation distortion compensation signals.

3. The transmitter of claim 2 wherein:

the adaptation subsystem comprises two or more adaptors configured to adaptively configure the plurality of digital predistorters based on the memory polynomial based digital baseband model of the plurality of digital predistorters; and

a number of adaptors in the two or more adaptors of the adaptation subsystem is less than a number of predistorters in the plurality of digital predistorters of the digital predistortion subsystem.

4. The transmitter of claim 2 wherein:

the adaptation subsystem comprises two or more adaptors configured to adaptively configure the plurality of digital predistorters based on the memory polynomial based digital baseband model of the plurality of digital predistorters; and

at least one adaptor of the two or more adaptors of the adaptation subsystem is configured to generate digital predistortion coefficients for at least two digital predistorters of the plurality of digital predistorters of the digital predistortion subsystem.

5. The transmitter of claim 4 wherein the at least two digital predistorters comprise:

a first digital predistorter configured to provide one of the plurality of predistorted digital input signals for one of the plurality of frequency bands of the concurrent multi-band signal; and

a second digital predistorter configured to provide one of the plurality of intermodulation distortion compensation signals for one of the plurality of intermodulation distortion frequency bands.

6. The transmitter of claim 5 wherein the at least one adaptor is configured to generate the digital predistortion coefficients for the at least two digital predistorters based on a combined digital feedback signal comprising a first component for the one of the plurality of frequency bands of the concurrent multi-band signal and a second component for the one of the plurality of intermodulation distortion frequency bands.

7. The transmitter of claim 6 further comprising an observation receiver configured to process the concurrent multi-band signal output by the power amplifier circuitry to provide the combined digital feedback signal such that a frequency band of the first component does not overlap with a frequency band of the second component within the combined digital feedback signal.

8. The transmitter of claim 2 wherein the adaptation subsystem comprises a single adaptor configured to adaptively configure the plurality of digital predistorters based on the memory polynomial based digital baseband model of the plurality of digital predistorters, wherein the memory polynomial based digital baseband model has a same set of predistortion coefficients for each of the plurality of digital predistorters.

9. The transmitter of claim 8 further comprising:

an observation receiver configured to process the concurrent multi-band signal output by the power amplifier circuitry to provide a combined digital feedback signal that is representative of both the plurality of frequency bands of the concurrent multi-band signal and the one or more intermodulation distortion frequency bands;

wherein the single adaptor is further configured to adaptively configure the plurality of digital predistorters based on the combined digital feedback signal.

10. The transmitter of claim 9 wherein the observation receiver comprises:

for each frequency band of the plurality of frequency bands of the concurrent multi-band signal, circuitry configured to process a component of the concurrent multi-band signal in the frequency band to provide a digital feedback signal for the frequency band centered at baseband;

for each intermodulation distortion frequency band of the one or more intermodulation distortion frequency bands, circuitry configured to process an intermodulation component in the intermodulation distortion frequency band to provide a digital feedback signal for the intermodulation distortion frequency band centered at a different intermediate frequency; and

combiner circuitry configured to combine the digital feedback signals for the plurality of frequency bands of the concurrent multi-band signal and the digital feedback signals for the one or more intermodulation distortion frequency bands to provide the combined digital feedback signal;

wherein the different intermediate frequencies for the one or more intermodulation distortion frequency bands are selected such that frequency bands of the digital feedback signals for the intermodulation distortion frequency bands do not overlap the frequency bands of the digital feedback signals for the plurality of frequency bands of the concurrent multi-band signal in the combined digital feedback signal.

11. The transmitter of claim 9 wherein the observation receiver comprises:

for each frequency band of the plurality of frequency bands of the concurrent multi-band signal, circuitry configured to process a component of the concurrent multi-band signal in the frequency band to provide a digital feedback signal for the frequency band centered at baseband;

for each intermodulation distortion frequency band of the one or more intermodulation distortion frequency bands, circuitry configured to process an intermodulation component in the intermodulation distortion frequency band to provide a digital feedback signal for the intermodulation distortion frequency band centered at baseband; and

combiner circuitry configured to combine the digital feedback signals for the plurality of frequency bands of the concurrent multi-band signal and the digital feedback signals for the one or more intermodulation distortion frequency bands to provide the combined digital feedback signal.

12. The transmitter of claim 8 further comprising:

an observation receiver configured to process the concurrent multi-band signal output by the power amplifier circuitry to provide a digital feedback signal that is representative of one of the plurality of frequency bands of the concurrent multi-band signal;

wherein the single adaptor is further configured to adaptively configure the plurality of digital predistorters based on the digital feedback signal.

13. The transmitter of claim 1 wherein the memory polynomial based digital baseband model defines a separate set of predistortion coefficients for each of the plurality of digital predistorters.

14. The transmitter of claim 1 wherein:

the memory polynomial based digital baseband model defines a separate set of predistortion coefficients for each of the plurality of digital predistorters; and

for each frequency band of the plurality of frequency bands of the concurrent multi-band signal and the one or more intermodulation distortion frequency bands, the memory polynomial based digital baseband model defines a single coefficient for all terms associated with a same non-linear order and memory depth.

15. The transmitter of claim 1 wherein the memory polynomial based digital baseband model defines a single set of predistortion coefficients for all of the plurality of digital predistorters.

16. The transmitter of claim 1 wherein:

the concurrent multi-band signal is a concurrent dual-band signal such that the plurality of frequency bands of the concurrent multi-band signal is a first frequency band and a second frequency band of the concurrent dual-band signal;

the plurality of digital input signals comprises a first digital input signal for the first frequency band of the concurrent dual-band signal and a second digital input signal for the second frequency band of the concurrent dual-band signal; and

the one or more intermodulation distortion frequency bands are a first third-order intermodulation distortion frequency band and a second third-order intermodulation distortion frequency band such that the one or more intermodulation distortion compensation signals are a first intermodulation distortion compensation signal for the first third-order intermodulation distortion frequency band and a second intermodulation distortion compensation signal for the second third-order intermodulation distortion frequency band.

17. The transmitter of claim 16 wherein:

the plurality of digital predistorters comprises separate digital predistorters for the first frequency band of the concurrent dual-band signal, the second frequency band of the concurrent dual-band signal, the first third-order intermodulation distortion frequency band, and the second third-order intermodulation distortion frequency band; and

the adaptation subsystem comprises two adaptors configured to adaptively configure the plurality of digital predistorters, wherein at least one adaptor of the two adaptors configures at least two of the separate digital predistorters.

18. The transmitter of claim 16 wherein:

the plurality of digital predistorters is four digital predistorters comprising;

a first digital predistorter configured to process the first digital input signal and the second digital input signal to provide a first predistorted digital input signal of the plurality of predistorted digital input signals;

a second digital predistorter configured to process the first digital input signal and the second digital input signal to provide a second predistorted digital input signal of the plurality of predistorted digital input signals;

a third digital predistorter configured to process the first digital input signal and the second digital input signal to provide a first intermodulation distortion compensation signal of the one or more intermodulation distortion compensation signals; and

a fourth digital predistorter configured to process the first digital input signal and the second digital input signal to provide a second intermodulation distortion compensation signal of the one or more intermodulation distortion compensation signals; and

the adaptation subsystem comprises;

a first adaptor configured to adaptively configure the first digital predistorter and the third digital predistorter based on the memory polynomial based digital baseband model of the plurality of digital predistorters; and

a second adaptor configured to adaptively configure the second digital predistorter and the fourth digital predistorter based on the memory polynomial based digital baseband model of the plurality of digital predistorters.

19. The transmitter of claim 18 wherein:

the first adaptor is further configured to adaptively configure the first digital predistorter and the third digital predistorter based on the memory polynomial based digital baseband model of the plurality of digital predistorters and a first combined digital feedback signal for the first frequency band of the concurrent dual-band signal and the first third-order intermodulation distortion frequency band; and

the second adaptor is further configured to adaptively configure the second digital predistorter and the fourth digital predistorter based on the memory polynomial based digital baseband model of the plurality of digital predistorters and a second combined digital feedback signal for the second frequency band of the concurrent dual-band signal and the second third-order intermodulation distortion frequency band.

20. The transmitter of claim 19 further comprising an observation receiver configured to process the concurrent dual-band signal output by the power amplifier circuitry to provide the first and second combined digital feedback signals.

21. The transmitter of claim 18 wherein, for N-th order nonlinearities and M-th order memory depth, the memory polynomial based digital baseband model is represented as:

22. The transmitter of claim 18 wherein, for N-th order nonlinearities and M-th order memory depth, the memory polynomial based digital baseband model is represented as:

23. The transmitter of claim 16 wherein:

the plurality of digital predistorters comprises separate digital predistorters for the first frequency band of the concurrent dual-band signal, the second frequency band of the concurrent dual-band signal, the first third-order intermodulation distortion frequency band, and the second third-order intermodulation distortion frequency band; and

the adaptation subsystem comprises a single adaptor configured to adaptively configure the plurality of digital predistorters.

24. The transmitter of claim 16 wherein:

the plurality of digital predistorters is four digital predistorters comprising;

a first digital predistorter configured to process the first digital input signal and the second digital input signal to provide a first predistorted digital input signal of the plurality of predistorted digital input signals;

a second digital predistorter configured to process the first digital input signal and the second digital input signal to provide a second predistorted digital input signal of the plurality of predistorted digital input signals;

a third digital predistorter configured to process the first digital input signal and the second digital input signal to provide a first intermodulation distortion compensation signal of the one or more intermodulation distortion compensation signals; and

a fourth digital predistorter configured to process the first digital input signal and the second digital input signal to provide a second intermodulation distortion compensation signal of the one or more intermodulation distortion compensation signals; and

the adaptation subsystem comprises a single adaptor configured to adaptively configure the first digital predistorter, the second digital predistorter, the third digital predistorter, and the fourth digital predistorter based on the memory polynomial based digital baseband model of the plurality of digital predistorters.

25. The transmitter of claim 24 wherein:

the single adaptor is further configured to adaptively configure the first digital predistorter, the second digital predistorter, the third digital predistorter, and the fourth digital predistorter based on the memory polynomial based digital baseband model of the plurality of digital predistorters and a combined digital feedback signal for the first and second frequency bands of the concurrent dual-band signal and the first and second third-order intermodulation distortion frequency bands.

26. The transmitter of claim 25 further comprising an observation receiver configured to process the concurrent dual-band signal output by the power amplifier circuitry to provide the combined digital feedback signal.

27. The transmitter of claim 24 wherein, for N-th order nonlinearities and M-th order memory depth, the memory polynomial based digital baseband model is represented as: