Method and apparatus for predistortion training in an amplifier utilizing predistortion
First Claim
1. A method for predistortion training in an amplifier using predistortion, the method comprising the steps of:
- receiving an input signal;
determining an amplitude of the input signal;
associating the amplitude of the input signal with an amplitude region;
receiving an amplification error for the input signal;
associating the amplification error with the amplitude region;
determining an average amplification error for the amplitude region;
modifying a predistortion LUT based on the average amplification error for the amplitude region; and
predistoring the input signal utilizing the LUT.
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Abstract
A method and apparatus for predistortion training in an amplifier using predistortion is provided herein. Predistortion takes place by collecting a series of envelope errors and averaging the envelope errors for various amplitude regions. LUT values are modified based on a curve-fit to the average amplitude values for each amplitude region. By utilizing a curve-fitting technique, the pitfalls of modifying individual LUT coefficients is avoided. Particularly, because the errors are collected in relatively broad regions and then averaged, the importance of exact correlation between a measured error and a specific LUT entry is significantly lessened.
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Citations
14 Claims
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1. A method for predistortion training in an amplifier using predistortion, the method comprising the steps of:
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receiving an input signal;
determining an amplitude of the input signal;
associating the amplitude of the input signal with an amplitude region;
receiving an amplification error for the input signal;
associating the amplification error with the amplitude region;
determining an average amplification error for the amplitude region;
modifying a predistortion LUT based on the average amplification error for the amplitude region; and
predistoring the input signal utilizing the LUT. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus comprising:
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a comparison block determining an amplification error;
a LUT re-trainer receiving an input signal having a given amplitude and amplification error and modifying LUT values based on the given amplitude and the amplification error, wherein the LUT re-trainer modifies LUT values by determining an average error for an amplitude region containing the given amplitude and modifying a predistortion LUT based on the average error; and
a LUT outputting the modified LUT values to a pre-distorter to be combined with a baseband input signal. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification