Architecture of nonlinear RF filter-based transmitter

Patent metadata

Field	Value
Publication number	US-9374044-B2
Application number	US-201113333391-A
Country	US
Kind code	B2
Filing date	Dec 21, 2011
Priority date	Dec 21, 2011
Publication date	Jun 21, 2016
Grant date	Jun 21, 2016

Abstract

Systems and methods for compensating for a non-linear characteristic of a non-linear filter in a transmit chain of a transmitter using predistortion are disclosed. In one embodiment, a transmitter includes a power amplifier configured to amplify a radio frequency input signal to provide an amplified radio frequency signal, a non-linear filter configured to filter the amplified radio frequency signal to provide an output signal of the transmitter, and a predistorter configured effect predistortion of the amplified radio frequency signal, where the predistortion compensates for a non-linear characteristic of the non-linear filter. In this manner, the output signal is as if the non-linear filter were a linear, or substantially liner, filter. The predistortion applied by the predistorter may be fixed or adaptive.

First claim

What is claimed is:

1. A transmitter comprising:
a power amplifier configured to amplify a radio frequency input signal to provide an amplified radio frequency signal;
a non-linear filter configured to filter the amplified radio frequency signal to provide an output signal; and
a predistorter configured to effect predistortion of the amplified radio frequency signal to compensate for a non-linear characteristic of the non-linear filter.

2. The transmitter of claim 1 wherein the non-linear filter has a linear characteristic in addition to the non-linear characteristic, and the predistortion effected by the predistorter compensates for the non-linear characteristic but not the linear characteristic of the non-linear filter.

3. The transmitter of claim 1 wherein the predistortion effected by the predistorter expands an operating region for the non-linear filter in which, due to the predistortion, the output signal is as if the non-linear filter were a linear filter.

4. The transmitter of claim 1 wherein the predistortion is a fixed predistortion.

5. The transmitter of claim 1 further comprising an adaptor configured to adaptively configure the predistorter to compensate for variations in the non-linear characteristic of the non-linear filter.

6. The transmitter of claim 1 wherein the predistorter is configured to apply the predistortion in an analog domain of the transmitter.

7. The transmitter of claim 1 wherein:
the predistorter has an input coupled to an output of the power amplifier and an output coupled to an input of the non-linear filter such that the predistorter is configured to receive the amplified radio frequency signal from the power amplifier and apply the predistortion to the amplified radio frequency signal to provide a predistorted, amplified radio frequency signal to the non-linear filter; and
the non-linear filter is configured to filter the predistorted, amplified radio frequency signal to provide the output signal.

8. The transmitter of claim 7 wherein the transmitter further comprises:
a second predistorter configured to effect predistortion of the radio frequency input signal to compensate for a non-linearity of the power amplifier; and
a second adaptor configured to adaptively configure the second predistorter to compensate for variations in the non-linearity of the power amplifier.

9. The transmitter of claim 1 wherein the predistorter is configured to apply the predistortion in a digital domain of the transmitter.

10. The transmitter of claim 1 wherein the predistorter is configured to predistort an input signal to compensate for the non-linear characteristic of the non-linear filter to thereby provide a first predistorted signal, and the transmitter further comprises:
a second predistorter configured to predistort the first predistorted signal to compensate for a non-linearity of the power amplifier to thereby provide a second predistorted signal; and
circuitry configured to process the second predistorted signal to provide the radio frequency input signal to the power amplifier.

11. The transmitter of claim 10 wherein the transmitter further comprises an adaptor configured to adaptively configure the second predistorter to compensate for variations in the non-linearity of the power amplifier.

12. The transmitter of claim 10 wherein the transmitter further comprises an adaptor configured to adaptively configure the predistorter to compensate for variations in the non-linear characteristic of the non-linear filter.

13. The transmitter of claim 12 wherein the adaptor is configured to adaptively configure the predistorter to compensate for variations in the non-linear characteristic of the non-linear filter based a comparison of the input signal and a feedback signal that is representative of the output signal from the non-linear filter.

14. The transmitter of claim 12 wherein the adaptor is configured to adaptively configure the predistorter to compensate for variations in the non-linear characteristic of the non-linear filter based on a comparison of an adaptor input signal that is representative of the amplified radio frequency signal input to the non-linear filter and a feedback signal that is representative of the output signal from the non-linear filter.

15. The transmitter of claim 10 wherein the transmitter further comprises:
a first adaptor configured to adaptively configure the predistorter to compensate for variations in the non-linear characteristic of the non-linear filter; and
a second adaptor configured to adaptively configure the second predistorter to compensate for variations in the non-linearity of the power amplifier.

16. The transmitter of claim 15 wherein the first adaptor is configured to adaptively configure the predistorter to compensate for variations in the non-linear characteristic of the non-linear filter based a comparison of the input signal and a feedback signal that is representative of the output signal from the non-linear filter.

17. The transmitter of claim 15 wherein the first adaptor is configured to adaptively configure the predistorter to compensate for variations in the non-linear characteristic of the non-linear filter based on a comparison of an adaptor input signal that is representative of the amplified radio frequency signal input to the non-linear filter and a feedback signal that is representative of the output signal from the non-linear filter.

18. The transmitter of claim 1 wherein the predistorter is further configured to effect predistortion of the radio frequency input signal to compensate for a non-linearity of the power amplifier.

19. The transmitter of claim 1 wherein the predistorter is configured to predistort an input signal to compensate for the non-linear characteristic of the non-linear filter and to compensate for a non-linearity of the power amplifier to thereby provide a predistorted signal, and the transmitter further comprises:
circuitry configured to process the predistorted signal to provide the radio frequency input signal to the power amplifier.

20. The transmitter of claim 1 wherein the transmitter is a wireless transmitter.

Assignees

• Jian Chunyun
• Bai Chunlong
• Sich Edward
• Ericsson Telefon Ab L M

Inventors

• Jian Chunyun
• Bai Chunlong
• Sich Edward

Classifications

• H03F2200/171

  A filter circuit coupled to the output of an amplifier · CPC title

• H04L27/368

  adaptive predistortion · CPC title

• H03F3/24

  of transmitter output stages · CPC title

• H03F2200/207

  A hybrid coupler being used as power measuring circuit at the output of an amplifier circuit · CPC title

• H03F1/3247 Primary

  using feedback acting on predistortion circuits (H03F1/3264 takes precedence) · CPC title