Digital predistorter for a wideband power amplifier and adaptation method
First Claim
1. A digital predistortion apparatus for predistorting an input digital signal to compensate for memoryless and memory non-linearities of a wideband power amplifier, comprising:
- a first predistorter for receiving the digital signal, the first predistorter being connected to the power amplifier through a digital to analog converter (DAC) and a frequency upconverter and including a first memoryless non-linearity part comprising a first look-up table (LUT) for compensating for the memoryless non-linearity and a first memory non-linearity part comprising a first finite impulse response (FIR) filter for compensating for the memory non-linearity; and
a second predistorter for receiving an feedback signal from the power amplifier through a frequency downconverter and an analog to digital converter (ADC), the second predistorter including a second memoryless non-linearity part comprising a second LUT having the same values as the first LUT for compensating for the memoryless non-linearity and a second memory non-linearity part comprising a second FIR filter comprising the same filtering coefficients as the first FIR filter for compensating for the memory non-linearity,wherein the first predistorter directly updates the first LUT and the second predistorter indirectly updates the first FIR filter using the second FIR filter.
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Abstract
An apparatus and method for eliminating the spurious signal of a non-linear amplifier in a base station transmitter of a mobile communication system are provided. A digital predistorter includes first and second predistorters, each having a memoryless non-linearity part using a look-up table and a memory non-linearity part using an finite impulse response (FIR) filter. The first predistorter adaptively updates the look-up tables, while the second predistorter adaptively updates the filtering coefficients of the FIR filters. According to another embodiment of the present invention, a digital predistorter has a memoryless non-linearity part using a look-up table and a memory non-linearity part using an FIR filter, and adaptively updates the look-up table and the filtering coefficients of the FIR filter.
52 Citations
20 Claims
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1. A digital predistortion apparatus for predistorting an input digital signal to compensate for memoryless and memory non-linearities of a wideband power amplifier, comprising:
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a first predistorter for receiving the digital signal, the first predistorter being connected to the power amplifier through a digital to analog converter (DAC) and a frequency upconverter and including a first memoryless non-linearity part comprising a first look-up table (LUT) for compensating for the memoryless non-linearity and a first memory non-linearity part comprising a first finite impulse response (FIR) filter for compensating for the memory non-linearity; and a second predistorter for receiving an feedback signal from the power amplifier through a frequency downconverter and an analog to digital converter (ADC), the second predistorter including a second memoryless non-linearity part comprising a second LUT having the same values as the first LUT for compensating for the memoryless non-linearity and a second memory non-linearity part comprising a second FIR filter comprising the same filtering coefficients as the first FIR filter for compensating for the memory non-linearity, wherein the first predistorter directly updates the first LUT and the second predistorter indirectly updates the first FIR filter using the second FIR filter. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of adapting a digital predistortion apparatus for predistorting an input digital signal to compensate for the memoryless and memory non-linearities of a wideband power amplifier that amplifies the digital signal, the digital predistortion apparatus comprising a first predistorter for receiving the digital signal, the first predistorter being connected to the power amplifier through a digital to analog converter (DAC) and a frequency upconverter and including a first memoryless non-linearity part for compensating for the memoryless non-linearity and a first memory non-linearity part for compensating for the memory non-linearity, and a second predistorter for receiving a feedback signal from the power amplifier through a frequency downconverter and an analog to digital converter (ADC), the second predistorter including a second memoryless non-linearity part for compensating for the memoryless non-linearity and a second memory non-linearity part for compensating for the memory non-linearity, the method comprising:
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receiving a single-tone training signal at the digital predistortion apparatus and adaptively updating a first look-up table (LUT) of the first memoryless non-linearity part; applying the update of the first LUT to a second LUT of the second memoryless non-linearity part; receiving a wideband training signal at the digital predistortion apparatus and adaptively updating filtering coefficients of a second finite impulse response (FIR) filter of the second memory non-linearity part; and applying the updated filtering coefficients to a first FIR filter of the first memory non-linearity part. - View Dependent Claims (9, 10, 11)
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12. A digital predistorter for predistorting an input digital signal to compensate for the memoryless and memory non-linearities of a wideband power amplifier that amplifies the digital signal, comprising:
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a memoryless non-linearity part comprising a look-up table (LUT) for compensating for the memoryless non-linearity and updating the LUT using a feedback signal from the power amplifier; and a memory non-linearity part comprising a finite impulse response (FIR) filter for compensating for the memory non-linearity and updating filtering coefficients of the FIR filter using the feedback signal, the digital predistorter being coupled to the power amplifier through a digital to analog converter (DAC) and a frequency upconverter, and predistorting the digital signal using the feedback signal received from the power amplifier through a frequency downconverter and an analog to digital converter (ADC). - View Dependent Claims (13, 14, 15, 16)
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17. A method of adapting a digital predistorter connected to a wideband power amplifier through a digital to analog converter (DAC) and a frequency upconverter, for predistorting an input digital signal using a feedback signal received from the power amplifier through a frequency downconverter and an analog to digital converter (ADC) to compensate for the memoryless and memory non-linearities of the power amplifier that amplifies the digital signal, the digital predistorter comprising a memoryless non-linearity part comprising a look-up table (LUT) for compensating for the memoryless non-linearity and updating the LUT using a feedback signal from the power amplifier, and a memory non-linearity part comprising a finite impulse response (FIR) filter for compensating for the memory non-linearity and updating filtering coefficients of the FIR filter using the feedback signal, the method comprising:
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receiving a single-tone training signal at the digital predistorter and adaptively updating the LUT of the memoryless non-linearity part; and receiving a wideband training signal at the digital predistorter and adaptively updating the filtering coefficients of the FIR filter in the memory non-linearity part. - View Dependent Claims (18, 19, 20)
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Specification