Waveform adaptable digital predistortion

• US 9,455,760 B1
• Filed: 07/02/2015
• Issued: 09/27/2016
• Est. Priority Date: 07/02/2015
• Status: Active Grant

• Current Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Original Assignee: Xilinx, Inc. (Advanced Micro Devices, Inc.)
• Inventors: Zhao, Hongzhi, Dick, Christopher H., Parekh, Hemang M., Barnes, Vincent C.
• Primary Examiner(s): Tse, Young T
• Application Number:
  US14/791,096
• Time in Patent Office: 453 Days
• Field of Search: 375/260, 375/296, 375/297, 381/94.1, 455/67.13, 455/114.2, 455/114.3
• US Class Current: 1/1
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 2201/3233 Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• 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: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/368 adaptive predistortion

Abstract

Apparatus, method therefor, generally related to signal preconditioning. In such an apparatus, a signal classifier block and a delay block are commonly coupled for receiving an input signal. The delay block is for providing a delayed version of the input signal. The signal classifier block is for classifying the input signal and generating a configuration signal having configuration information for digital predistortion (“DPD”) engine parameterization in response to the input signal classification. A DPD engine is for receiving the delayed version of the input signal and the configuration signal and for providing a predistorted output signal.

Claims

1. An apparatus for signal preconditioning, comprising:

a signal classifier block and a delay block commonly coupled for receiving an input signal;

the delay block for providing a delayed version of the input signal;

the signal classifier block for classifying the input signal and generating a configuration signal having configuration information for digital predistortion (DPD) engine parameterization in response to the input signal classification; and

a DPD engine for receiving the delayed version of the input signal and the configuration signal and for providing a predistorted output signal;

wherein the signal classifier block comprises;

a Fourier Transform block configured for receiving sets of samples for transforming the sets of samples into a frequency domain for providing spectral information for the sets of samples; and

a signal analyzer configured for receiving the spectral information and analyzing the spectral information for classification using signal classification information including meta-data for a plurality of different waveforms for providing the configuration signal.

2. The apparatus according to claim 1, wherein the predistorted output signal is used for reducing effects of nonlinearity of a power amplifier coupled downstream of the DPD engine;

and wherein the signal classifier block further comprises;

a parser block for receiving the input signal for providing data blocks from complex data samples obtained from the input signal; and

;

a windowing block for receiving the data blocks for providing sets of windowed samples for the data blocks as the sets of samples;

wherein the Fourier Transform block is for receiving the sets of windowed samples as the sets of samples for providing the spectral information for the sets of windowed samples.

3. The apparatus according to claim 2, wherein the parser block is a buffer for buffering data of the input signal for outputting the data blocks.

4. The apparatus according to claim 3, wherein the data blocks are overlapping data blocks.

5. The apparatus according to claim 3, wherein the data blocks are non-overlapping data blocks.

6. The apparatus according to claim 2, wherein the spectral information is provided in parallel to the signal analyzer.

7. The apparatus according to claim 2, wherein

a portion of the meta-data for the input signal used in providing the configuration information enhances operation of the power amplifier by compensating for nonlinearity thereof.

8. The apparatus according to claim 7, wherein the meta-data comprises frequency bandwidth information and modulation information for a plurality of different signal types for the plurality of different waveforms.

9. The apparatus according to claim 7, wherein the meta-data comprises frequency bandwidth information, modulation information, and power-level information for a plurality of different signal types for the plurality of different waveforms.

10. The apparatus according to claim 2, wherein the DPD engine comprises a parameter estimation engine for receiving the delayed version of the input signal, the configuration signal, and a feedback signal for updating of predistortion coefficients.

11. The apparatus according to claim 10, wherein:

the feedback signal has predistortion coefficient adaptation information;

the configuration information is for an identified signal type of the input signal for converting the parameter estimation engine into a special-purpose parameter estimation engine for the signal type identified for updating of the predistortion coefficients; and

the signal type is selected from a group consisting of WCDMA signals, LTE signals, GSM signals, and CDMA200 signals.

12. The apparatus according to claim 10, wherein:

the DPD engine further comprises a predistortion datapath block for receiving the delayed version of the input signal and the predistortion coefficients; and

the predistortion datapath block comprises a nonlinear filter coupled for application of the predistortion coefficients as filter coefficients for the nonlinear filter.

13. The apparatus according to claim 10, wherein:

the DPD engine further comprises a predistortion datapath block for receiving the delayed version of the input signal and the predistortion coefficients; and

the predistortion datapath block comprises;

a nonlinear filter; and

a predistortion coefficient-to-lookup table builder for receiving the predistortion coefficients and assigning the predistortion coefficients received to a lookup table of the nonlinear filter;

wherein the lookup table of the nonlinear filter is coupled for receiving of the predistortion coefficients as filter coefficients.

14. The apparatus according to claim 13, wherein the lookup table is segregated from at least one other lookup table of the nonlinear filter according to power level for a same modulation type and a same bandwidth as between the lookup table and the at least one other lookup table.

15. The apparatus according to claim 13, wherein the lookup table is segregated from at least one other lookup table of the nonlinear filter according to modulation type and at least one of power level for a same bandwidth or bandwidth for a same power level as between the lookup table and the at least one other lookup table.

16. The apparatus according to claim 13, wherein the lookup table is segregated from at least one other lookup table of the nonlinear filter according to power level and bandwidth for a same modulation type as between the lookup table and the at least one other lookup table.

17. A transmission system comprising the apparatus according to claim 13, the system further comprising:

a signal conversion front end for receiving the predistorted output signal for providing an analog input;

the power amplifier for receiving the analog input for power amplifying thereof for providing an analog output; and

a signal adaptation block for receiving the analog output for providing the feedback signal.

18. A method for signal preconditioning, comprising:

receiving an input signal by a signal classifier block and a delay block;

delaying the input signal by the delay block for providing a delayed version thereof;

classifying the input signal with the signal classifier block;

generating a configuration signal by the signal classifier block;

the configuration signal generated having configuration information for digital predistortion (DPD) engine parameterization in response to the input signal classification;

receiving the delayed version of the input signal and the configuration signal by a DPD engine; and

predistorting the input signal by the DPD engine for providing a predistorted output signal;

wherein the classifying and the generating by the signal classifier block comprise;

transforming sets of samples with a Fourier Transform block for transforming the sets of samples into a frequency domain for providing spectral information for the sets of samples;

receiving the spectral information and signal classification data by a signal analyzer; and

analyzing the spectral information by the signal analyzer for classification using the signal classification data including meta-data for a plurality of different waveforms for providing the configuration signal.

19. The method according to claim 18, further comprising outputting the predistorted output signal from the DPD engine for reducing nonlinearity in an analog output of a power amplifier coupled downstream to receive the predistorted output signal;

and wherein the classifying and the generating by the signal classifier block further comprise;

parsing the input signal with a parser block for providing data blocks from complex data samples obtained from the input signal;

receiving the data blocks by a windowing block;

windowing the data blocks with the windowing block for providing corresponding sets of windowed samples for the data blocks as the sets of samples; and

receiving the sets of windowed samples by the Fourier Transform block;

wherein the transforming of the sets of windowed samples with the Fourier Transform block is for providing the spectral information for each set of the sets of windowed samples; and

wherein the signal classification data for the input signal is used by the signal analyzer for providing the configuration information to enhance operation of the power amplifier by compensating for the nonlinearity thereof.

20. The method according to claim 19, wherein the predistorting comprises:

estimating parameters using the delayed version of the input signal, the configuration signal and a feedback signal for providing predistortion coefficients; and

nonlinear filtering the delayed version of the input signal using the predistortion coefficients for providing the predistorted output signal;

wherein the feedback signal is for providing predistortion coefficient adaptation information associated with the analog output for updating the predistortion coefficients.