Digital pre-distortion filter system and method

Patent metadata

Field	Value
Publication number	US-2016112222-A1
Application number	US-201514923709-A
Country	US
Kind code	A1
Filing date	Oct 27, 2015
Priority date	Sep 15, 2011
Publication date	Apr 21, 2016
Grant date	—

Abstract

A digital predistorter for improving the performance of a narrow passband filter near the output is disclosed. The digital predistorter provides amplitude correction to the signal based on the characteristics of the passband filter. A filter group delay predistorter may also be employed to correct group delay variation introduced by the narrow passband filter.

First claim

21 . An apparatus of a device for wireless communication, the apparatus comprising:
predistortion circuitry to pre-distort digital baseband samples for a component carrier and generate a predistorted baseband signal for the component carrier, the predistortion circuitry to perform amplitude correction based on a roll-off characteristic associated with the component carrier; combiner circuitry to generate a digital multicarrier signal from the predistorted baseband signals; group-delay (GD) predistortion circuitry to provide an inverse group delay characteristic to the multicarrier signal; crest-factor reduction (CFR) circuitry to reduce a crest factor of the multicarrier signal; and transceiver circuitry to generate an orthogonal frequency division multiplexed (OFDM) signal, from the multicarrier signal, for the component carrier, for transmission, after CFR.

22 . The apparatus of claim 21 wherein the GD predistortion circuitry comprises an all-pass infinite impulse response (IIR) filter.

23 . The apparatus of claim 22 wherein the transceiver circuitry comprises an output band-pass filter, and
wherein the IIR filter of the GD predistortion circuitry is configured to compensate for group delay of the band-pass filter.

24 . The apparatus of claim 23 wherein the predistortion circuitry comprises a complex finite impulse response (FIR) filter structure that is configured to compensate for an amplitude response of the band-pass filter.

25 . The apparatus of claim 24 wherein the complex IIR filter structure is configured to provide inverse amplitude waveform predistortion based on location of the component carrier relative to a roll-off characteristic of the band-pass filter.

26 . the apparatus of claim 23 wherein the transceiver further includes an output combiner duplexer, and
wherein the IIR filter of the GD predistortion circuitry to generate group delay compensation to compensate for group delay deviation present in the output combiner duplexer.

27 . The apparatus of claim 26 wherein the output combiner duplexer is configured to be coupled to one or more antennas.

28 . The apparatus of claim 23 further comprising a digital to analog converter (DAC) to convert the multicarrier signal, after CFR, to analog signals for subsequent generation of radio-frequency signals,
wherein the output band-pass filter is configured to filter the radio-frequency signals prior to transmission.

29 . The apparatus of claim 28 wherein the CFR circuitry is configured to reduce a peak-to-average power ratio (PAR) of the multicarrier signal.

30 . The apparatus of claim 21 wherein the predistortion circuitry is configured to pre-distort the digital baseband samples for a plurality of component carriers and generate a predistorted baseband signal for each of the component carriers, the predistortion circuitry to perform amplitude correction based on a roll-off characteristic associated with each of the component carriers.

31 . A method, performed by processing circuitry and transceiver circuitry, the method comprising:
pre-distorting digital baseband samples for a component carrier to generate a predistorted baseband signal for the component carrier, the pre-distorting comprising an amplitude correction based on a roll-off characteristic associated with the component carrier; generating a digital multicarrier signal from the predistorted baseband signals; imposing an inverse group delay (GD) characteristic to the multicarrier signal; reducing a crest factor of the multicarrier signal; and generating an orthogonal frequency division multiplexed (OFDM) signal, from the multicarrier signal, for the component carrier, for transmission, after CFR.

32 . The method of claim 31 wherein imposing an inverse GD characteristic is performed by an all-pass infinite impulse response (IIR) filter.

33 . The method of claim 32 wherein the IIR filter is configured to compensate for group delay of a band-pass filter.

34 . The method of claim 33 wherein the pre-distorting is performed by a complex finite impulse response (FIR) filter structure that is configured to compensate for an amplitude response of the band-pass filter.

35 . The method of claim 34 wherein the complex IIR filter structure is configured to provide inverse amplitude waveform predistortion based on location of the component carrier relative to a roll-off characteristic of the band-pass filter.

36 . The method of claim 33 wherein pre-distorting further comprises generating group delay compensation to compensate for group delay deviation present in an output combiner duplexer.

37 . The method of claim 33 further comprising converting the multicarrier signal, after CFR, to analog signals for subsequent generation of radio-frequency signals,
wherein the output band-pass filter is configured to filter the radio-frequency signals prior to transmission.

38 . The method of claim 37 wherein reducing the crest factor comprises reducing a peak-to-average power ratio (PAR) of the multicarrier signal.

39 . The method of claim 31 wherein the pre-distorting further comprises:
pre-distorting the digital baseband samples for a plurality of component carriers and generate a predistorted baseband signal for each of the component carriers; and
performing amplitude correction based on a roll-off characteristic associated with each of the component carriers.

40 . An apparatus of a device for wireless communication, the apparatus comprising:
predistortion circuitry to pre-distort digital baseband samples for each of a plurality of component carriers and generate a predistorted baseband signal for each component carrier, the predistortion circuitry to perform amplitude correction based on a roll-off characteristic associated with each component carrier; combiner circuitry to generate a digital multicarrier signal from the predistorted baseband signals; group-delay (GD) predistortion circuitry to provide an inverse group delay characteristic to the multicarrier signal; crest-factor reduction (CFR) circuitry to reduce a crest factor of the multicarrier signal; and transceiver circuitry, including an output band-pass filter, to generate an orthogonal frequency division multiplexed (OFDM) signal, from the multicarrier signal, for each component carrier, for transmission, after CFR.

41 . The apparatus of claim 40 wherein the GD predistortion circuitry comprises an all-pass infinite impulse response (IIR) filter configured to compensate for group delay of the band-pass filter, and
wherein the predistortion circuitry comprises a complex finite impulse response (FIR) filter structure that is configured to compensate for an amplitude response of the band-pass filter.

42 . The apparatus of claim 41 wherein the complex IIR filter structure is configured to provide inverse amplitude waveform predistortion based on location of the component carrier relative to a roll-off characteristic of the band-pass filter.

Assignees

• Intel Corp

Inventors

• Pashay-Kojouri Majid
• Maiden Richard

Classifications

• H04L25/49 Primary

  using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels {; Baseband coding techniques specific to data transmission systems (spectral shaping H04L25/03828)} · CPC title

• H03F3/193

  with field-effect devices (H03F3/195 takes precedence) · CPC title

• H04L25/03834

  using pulse shaping · CPC title

• H04L2025/03503

  as a combination of feedback and prediction filters · CPC title

• H03F2203/45318

  the AAC comprising a cross coupling circuit, e.g. two extra transistors cross coupled · CPC title