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 for compensating for the memoryless non-linearity using a first look-up table (LUT) and a first memory non-linearity part for compensating for the memory non-linearity using a first finite impulse response (FIR) filter; 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 for compensating for the memoryless non-linearity using a second LUT having the same values as the first LUT and a second memory non-linearity part for compensating for the memory non-linearity using a second FIR filter having the same filtering coefficients as the first FIR filter, 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.
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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 for compensating for the memoryless non-linearity using a first look-up table (LUT) and a first memory non-linearity part for compensating for the memory non-linearity using a first finite impulse response (FIR) filter; 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 for compensating for the memoryless non-linearity using a second LUT having the same values as the first LUT and a second memory non-linearity part for compensating for the memory non-linearity using a second FIR filter having the same filtering coefficients as the first FIR filter, 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 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 for compensating for the memoryless non-linearity and a second memory non-linearity part for compensating for the memory non-linearity, the method comprising the steps of:
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(1) 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;
(2) applying the update of the first LUT to a second LUT of the second memoryless non-linearity part;
(3) 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
(4) 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 for compensating for the memoryless non-linearity using a look-up table (LUT) and adapting the LUT using a feedback signal from the power amplifier; and
a memory non-linearity part for compensating for the memory non-linearity using a finite impulse response (FIR) filter and adapting 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 for compensating for the memoryless non-linearity using a look-up table (LUT) and adapting the LUT using a feedback signal from the power amplifier, and a memory non-linearity part for compensating for the memory non-linearity using a finite impulse response (FIR) filter and adapting filtering coefficients of the FIR filter using the feedback signal, the method comprising the steps of:
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(a) receiving a single-tone training signal at the digital predistorter and adaptively updating the LUT of the memoryless non-linearity part; and
(b) 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