Adaptive linearization of power amplifiers
First Claim
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1. A method for adaptively compensating for a distortion characteristic of a power amplifier, the method comprising the steps of:
- measuring the distortion characteristic across the power amplifier during amplification of a distortion detection signal, the distortion detection signal having a defined input power characteristic;
calculating a relationship between the measured distortion characteristic and input power;
updating a predistortion lookup table in accordance with the calculated relationship; and
wherein the step of measuring is performed using a pair of detectors, a first detector of the pair of detectors connected to an input terminal of the power amplifier, and a second detector of the pair of detectors connected to an output terminal of the power amplifier.
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Abstract
A method and apparatus adaptively compensates for nonlinearities of a power amplifier by measuring a distortion characteristic across the power amplifier during amplification of a distortion detection signal. The distortion detection signal has a well-defined input power versus time relationship, such as ramp-up signal or ramp-down signal. Due to this well-defined relationship, the distortion characteristic can be calculated as a function of the input power level. This calculated function is then utilized to update a predistortion lookup table.
314 Citations
33 Claims
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1. A method for adaptively compensating for a distortion characteristic of a power amplifier, the method comprising the steps of:
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measuring the distortion characteristic across the power amplifier during amplification of a distortion detection signal, the distortion detection signal having a defined input power characteristic;
calculating a relationship between the measured distortion characteristic and input power;
updating a predistortion lookup table in accordance with the calculated relationship; and
wherein the step of measuring is performed using a pair of detectors, a first detector of the pair of detectors connected to an input terminal of the power amplifier, and a second detector of the pair of detectors connected to an output terminal of the power amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for linearizing a power amplifier, the apparatus comprising:
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at least one detector adapted to measure a distortion characteristic across a power amplifier during amplification of a distortion detection signal, the distortion detection signal having a known input power characteristic;
a processor coupled to the at least one detector, the processor adapted to calculate a relationship between the measured distortion characteristic and input power of the power amplifier;
a predistortion lookup table storing predistortion coefficients, the processor being adapted to update the predistortion coefficients in accordance with the calculated relationship to adaptively compensate for the measured distortion characteristic; and
wherein the at least one detector comprises a pair of detectors, a first detector of the pair of detectors connected to an output of the power amplifier, and a second detector of the pair of detectors connected to an input of the power amplifier. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 33)
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27. An apparatus for linearizing a power amplifier, the apparatus comprising:
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at least one detector adapted to measure a distortion characteristic across a power amplifier during amplification of a distortion detection signal, the distortion detection signal having a known input power characteristic;
a processor coupled to the at least one detector, the processor adapted to calculate a relationship between the measured distortion characteristic and input power;
a predistortion lookup table storing predistortion coefficients, the processor being adapted to update the redistortion coefficients in accordance with the calculated relationship to adaptively compensate for the measured distortion characteristic; and
wherein the at least one detector comprises a pair of phase detectors, a first phase detector of the pair of phase detectors connected to an output of the power amplifier, and a second phase detector of the pair of detectors connected to an input of the power amplifier. - View Dependent Claims (28, 29)
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30. An apparatus for linearizing a power amplifier, the apparatus comprising:
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at least one detector adapted to measure a distortion characteristic across a power amplifier during amplification of a distortion detection signal, the distortion detection signal having a known input power characteristic;
a processor coupled to the at least one detector, the processor adapted to calculate a relationship between the measured distortion characteristic and input power;
a predistortion lookup table storing predistortion coefficients, the processor being adapted to update the predistortion coefficients in accordance with the calculated relationship to adaptively compensate for the measured distortion characteristic; and
wherein the at least one detector comprises a pair of envelope detectors, a first envelope detector of the pair of envelope detectors connected to an output of the power amplifier, and a second envelope detector of the pair of envelope detectors connected to an input of the power amplifier. - View Dependent Claims (31, 32)
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Specification