High power amplifier linearization method using extended saleh model predistortion
First Claim
1. A method of linearizing an output signal of an amplifier distorting an input signal, the output signal being derived from the input signal, the method comprising the steps of,closed-form computing predistortion using an amplitude closed-form equation and a phase closed-form equation modeling distortion of the amplifier and using a set of predetermined coefficients of the closed-form equations for canceling distortion caused by the amplifier, predistorting the input signal by the predistortion for providing a predistorted input signal, and amplifying the predistorted input signal to generate the output signal, the output signal being linearized to the input signal.
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Abstract
A predistortion method uses an extended Saleh model for linearizing the output of nonlinear high power amplifiers having inherent amplitude modulation to amplitude modulation distortion, and inherent amplitude modulation to phase modulation distortion, during conversions of an input signal to an output signal. A complex baseband linearizer provides predistortion at baseband for reducing spectral regrowth and improves bit error performance. The predistortion effects are matched to the amplifier distortions to cancel out the distortions to provide linearized conversions. The extended Saleh model provides a general solution using selected coefficients matched to distortion effects of a particular amplifier.
43 Citations
6 Claims
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1. A method of linearizing an output signal of an amplifier distorting an input signal, the output signal being derived from the input signal, the method comprising the steps of,
closed-form computing predistortion using an amplitude closed-form equation and a phase closed-form equation modeling distortion of the amplifier and using a set of predetermined coefficients of the closed-form equations for canceling distortion caused by the amplifier, predistorting the input signal by the predistortion for providing a predistorted input signal, and amplifying the predistorted input signal to generate the output signal, the output signal being linearized to the input signal.
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5. A method of linearizing an output signal of an amplifier distorting an input signal, the output signal being derived from the input signal, the method comprising the steps of,
closed-form computing predistortion using a set of predetermined coefficients for canceling distortion caused by the amplifier, predistorting the input signal by the predistortion for providing a predistorted input signal, amplifying the predistorted input signal to generate the output signal, the output signal being linearized to the input signal, the distortion being phase and amplitude distortion, the predistortion comprising phase and amplitude predistortion, and the closed-form computing step using phase and amplitude closed-form equations to compute the phase and amplitude predistortions, measuring amplitude and phase responses of the amplifier during modulation of the amplitude modulated input signal, and selecting the predetermined coefficients so that the computed phase and amplitude predistortion inversely matches the amplitude and phase responses of the amplifier, wherein the amplitude closed-form equation is: -
the phase closed-form equation is;
the predetermined coefficients are a0, a1, b0, b1, α
0, α
1, β
0 and β
1.
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6. A method of linearizing an output signal of an amplifier distorting an input signal, the output signal being derived from the input signal, the method comprising the steps of,
closed-form computing predistortion using a set of predetermined coefficients for canceling distortion caused by the amplifier, predistorting the input signal by the predistortion for providing a predistorted input signal, amplifying the predistorted input signal to generate the output signal, the output signal being linearized to the input signal, the input signal being a baseband input signal, converting the baseband input signal into a complex input signal, predistorting the complex input signal to provide a predistorted complex signal at baseband, up converting the complex input signal into an intermediate frequency complex signal by modulation with an intermediate frequency, mixing the predistorted complex signal with the intermediate frequency complex signal to provide a mixed predistorted signal, and up converting the mixed predistorted signal into the predistorted input signal by mixing the mixed predistorter signal with a radio frequency.
Specification