Wide bandwidth digital predistortion system with reduced sampling rate
AssigneeDali Systems Co. Ltd.
InventorsWan-Jong Kim, Shawn Patrick Stapleton
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Abstract
A digital predistortion linearization method is provided for increasing the instantaneous or operational bandwidth for RF power amplifiers employed in wideband communication systems. Embodiments of the present invention provide a method of increasing DPD linearization bandwidth using a feedback filter integrated into existing digital platforms for multi-channel wideband wireless transmitters. An embodiment of the present invention utilizes a DPD feedback signal in conjunction with a low power band-pass filter in the DPD feedback path.
Claims18
A wideband communications system including:
- a digital predistorter (DPD) operable to receive an input signal, wherein the DPD is characterized by a first bandwidth;
- a filter characterized by a second bandwidth coupled to the output of the DPD;
- a digital-to-analog converter coupled to the output of the filter;
- a modulator coupled to the output of the digital-to-analog converter;
- a power amplifier coupled to the output of the modulator;
- a band-pass filter characterized by a third bandwidth coupled to the output of the power amplifier;
- a down-converter coupled to the output of the band-pass filter;
- an analog-to-digital converter (ADC) coupled to the output of the down-converter, wherein the ADC is characterized by a sampling rate value less than a value of the first bandwidth;
- and
- a digital filter coupled to the polynomial function generators in the indirect learning algorithm.
A communications system comprising:
- a digital predistorter (DPD) operable to receive an input signal, wherein the input signal is characterized by a bandwidth of 20 MHz and the DPD is characterized by a bandwidth of greater than 100 MHz;
- a digital filter coupled to the output of the DPD, wherein the digital filter is characterized by a bandwidth between 30 MHz and 50 MHz;
- a digital-to-analog converter coupled to the output of the digital filter;
- a modulator coupled to the output of the digital-to-analog converter;
- a power amplifier coupled to the output of the modulator;
- a radio frequency (RF) band-pass filter coupled to the output of the power amplifier and characterized by a bandwidth less than 100 MHz;
- an analog-to-digital converter (ADC) coupled to the output of the RF band-pass filter, wherein the ADC is characterized by a sampling rate less than or equal to 100 Msps;
- and
- a digital filter coupled to the polynomial function generator in the indirect learning algorithm.
A method of operating a communications system, the method comprising:
- receiving a signal at a digital predistorter (DPD);
- introducing predistortion to the signal using the DPD;
- filtering the predistorted signal using a digital filter;
- converting the filtered signal to an analog signal;
- modulating the analog signal;
- amplifying the modulated signal;
- coupling a portion of the amplified signal to provide a feedback signal;
- filtering the feedback signal using a band-pass filter;
- downconverting the filtered feedback signal;
- converting the downconverted signal to a digital signal;
- and
- providing the digital signal to the DPD.
Dependencies are inferred from the claim text.