Multi-band radio-frequency digital predistortion

Patent metadata

Field	Value
Publication number	US-2016119004-A1
Application number	US-201614989934-A
Country	US
Kind code	A1
Filing date	Jan 7, 2016
Priority date	May 24, 2013
Publication date	Apr 28, 2016
Grant date	—

Abstract

Systems and methods for radio frequency digital predistortion in a multi-band transmitter are disclosed. In one embodiment, the multi-band transmitter includes a digital upconversion system configured to digitally upconvert digital input signals to provide digital radio frequency signals. Each digital input signal and thus each digital radio frequency signal corresponds to a different band of a multi-band transmit signal to be transmitted by the multi-band transmitter. The multi-band transmitter also includes a radio frequency digital predistortion system configured to digitally predistort the digital radio frequency signals to provide predistorted digital radio frequency signals, and a combiner configured to combine the predistorted digital radio frequency signals to provide a multi-band predistorted digital radio frequency signal.

First claim

What is claimed is:

1 . A multi-band transmitter, comprising:
a radio frequency digital predistortion system operative to predistort a plurality of digital radio frequency signals to thereby generate a plurality of predistorted digital radio frequency signals corresponding to a plurality of bands of a multi-band transmit signal to be transmitted by the multi-band transmitter, comprising:
a plurality of radio frequency digital predistortion actuators comprising a separate radio frequency digital predistortion actuator for each band of the plurality of bands of the multi-band transmit signal, each radio frequency digital predistortion actuator being operative to generate a predistorted digital radio frequency signal by directly synthesizing a plurality of distortion products based on the plurality of digital radio frequency signals and a plurality of configurable weights.

2 . The multi-band transmitter of claim 1 , wherein the plurality of distortion products comprises self-distortion products, intra-band distortion products, and inter-band distortion products.

3 . The multi-band transmitter of claim 1 , wherein the plurality of distortion products comprises at least two distortion products selected from a group consisting of:
one or more self-distortion products; one or more intra-band distortion products; and one or more inter-band distortion products.

4 . The multi-band transmitter of claim 1 , further comprising:
a digital upconversion system operative to generate the plurality of digital radio frequency signals by digitally upconverting a plurality of digital input signals, the digital upconversion system comprising a separate digital upconversion subsystem for each band of the plurality of bands of the multi-band transmit signal.

5 . The multi-band transmitter of claim 4 , wherein the separate digital upconversion subsystems for the plurality of bands of the multi-band transmit signal comprise at least one separate digital upconversion subsystem comprising a rate change filter.

6 . The multi-band transmitter of claim 4 , further comprising:
combiner circuitry operative to combine the plurality of predistorted digital radio frequency signals to generate a multi-band predistorted digital radio frequency signal.

7 . The multi-band transmitter of claim 6 , further comprising:
a multi-band signal processing system operative to generate a multi-band predistorted analog radio frequency signal from the multi-band predistorted digital radio frequency signal; and power amplifier circuitry operative to amplify the multi-band predistorted analog radio frequency signal to provide the multi-band transmit signal.

8 . The multi-band transmitter of claim 1 , further comprising a training system operative to train the radio frequency digital predistortion system, the training system comprising:
for each band of the plurality of bands of the multi-band transmit signal, a separate baseband training subsystem for the band of the multi-band transmit signal is operative to adjust the plurality of configurable weights for the separate radio frequency digital predistortion actuator for the band of the multi-band transmit signal based on a delayed baseband equivalent signal of the predistorted digital radio frequency signal for the band of the multi-band transmit signal and an output signal generated by the separate baseband training subsystem based on a plurality of digital baseband feedback signals for the plurality of bands of the multi-band transmit signal.

9 . The multi-band transmitter of claim 8 , wherein, for each band of the plurality of bands of the multi-band transmit signal, the separate baseband training subsystem for the band of the multi-band transmit signal is further operative to adjust the plurality of configurable weights for the separate radio frequency digital predistortion actuator for the band of the multi-band transmit signal by directly synthesizing a plurality of baseband equivalent versions of the plurality of distortion products based on the plurality of digital baseband feedback signals.

10 . The multi-band transmitter of claim 9 , wherein the plurality of distortion products comprises self-distortion products, intra-band distortion products, and inter-band distortion products.

11 . The multi-band transmitter of claim 8 , wherein, for each band of the plurality of bands of the multi-band transmit signal, the training system further comprises:
bandpass filtering circuitry operative to filter a digital representation of the multi-band transmit signal to provide a filtered digital radio frequency feedback signal for the band of the multi-band transmit signal; tuning circuitry operative to tune the filtered digital radio frequency feedback signal for the band of the multi-band transmit signal to provide an initial baseband feedback signal for the band of the multi-band transmit signal; and decimation filter circuitry operative to down-sample the initial baseband feedback signal for the band of the multi-band transmit signal to provide a baseband feedback signal for the band of the multi-band transmit signal.

12 . The multi-band transmitter of claim 11 , wherein, for each band of the plurality of bands of the multi-band transmit signal, the training system further comprises:
tuning circuitry operative to tune the predistorted digital radio frequency signal for the band of the multi-band transmit signal to provide an initial baseband equivalent signal for the band of the multi-band transmit signal; decimation filter circuitry operative to down-sample the initial baseband equivalent signal for the band of the multi-band transmit signal to provide a down-sampled baseband equivalent signal for the band of the multi-band transmit signal; and delay circuitry operative to delay the down-sampled baseband equivalent signal for the band of the multi-band transmit signal to provide the delayed baseband equivalent signal for the predistorted digital radio frequency signal for the band of the multi-band transmit signal.

13 . The multi-band transmitter of claim 12 , wherein, for each band of the plurality of bands of the multi-band transmit signal, the training system further comprises:
subtractor circuitry operative to generate an error signal for the band of the multi-band transmit signal based on a difference between the delayed baseband equivalent signal for the band of the multi-band transmit signal and the output signal generated by the separate baseband training subsystem for the band of the multi-band transmit signal.

14 . The multi-band transmitter of claim 13 , wherein for each band of the plurality of bands of the multi-band transmit signal, the plurality of configurable weights for the separate radio frequency digital predistortion actuator for the band of the multi-band transmit signal are adjusted to minimize the error signal for the band of the multi-band transmit signal.

15 . A method of operation of a training system operative to train a radio frequency digital predistortion system of a multi-band transmitter, the radio frequency digital predistortion system operative to predistort a plurality of digital radio frequency signals to thereby generate a plurality of predistorted digital radio frequency signals corresponding to a plurality of bands of a multi-band transmit signal output by the multi-band transmitter, the radio frequency digital predistortion system comprising a separate radio frequency digital predistortion actuator for each band of the plurality of bands of the multi-band transmit signal, each separate radio frequency digital predistortion actuator being op

Assignees

• Ericsson Telefon Ab L M

Inventors

• Rollins Mark Edward

Classifications

• H03F1/3247 Primary

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

• H03F2200/111

  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 title

• H03F1/3294

  Acting on the real and imaginary components of the input signal · CPC title

• H03F1/3252

  using multiple parallel paths between input and output (H03F1/3258, H03F1/3282, H03F1/3294 take precedence) · CPC title

• H03F2201/3203

  the amplifier comprising means for back off control in order to reduce distortion · CPC title