Architecture and implementation methods of digital predistortion circuitry
First Claim
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1. A predistorter configured for use with an RF power amplifier, the predistorter comprising:
- a vector modulator configured to receive an RF input signal and apply a correction thereto using correction factors;
a data structure coupled to the vector modulator and storing the correction factors;
the data structure including a first pair of look-un tables configured for storing amplitude and phase correction factors, the correction factors of the first pair of look-up tables compensating for amplitude and phase non-linearities in the responses of both the RF power amplifier and the vector modulator;
the data structure further including a second pair of look-up tables configured for storing correction factors to compensate for memory effects in the response of the RF power amplifier.
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Abstract
A predistorter including a modulator configured for use with an RF power amplifier or in an amplifier system that combines in a data structure correction factors for amplitude and phase non-linearities in the responses of the amplifier and the modulator. Correction factors for memory effects in the response of the RF power amplifier may also be calculated within the data structure from scale factors transferred into the data structure. Such a calculation may be based on a scaled polynomial. A circuit for applying the difference equation to the correction factors may also be included.
128 Citations
50 Claims
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1. A predistorter configured for use with an RF power amplifier, the predistorter comprising:
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a vector modulator configured to receive an RF input signal and apply a correction thereto using correction factors; a data structure coupled to the vector modulator and storing the correction factors; the data structure including a first pair of look-un tables configured for storing amplitude and phase correction factors, the correction factors of the first pair of look-up tables compensating for amplitude and phase non-linearities in the responses of both the RF power amplifier and the vector modulator; the data structure further including a second pair of look-up tables configured for storing correction factors to compensate for memory effects in the response of the RF power amplifier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A predistorter configured for use with an RF power amplifier, the predistorter comprising:
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a vector modulator configured to receive an RF input signal and apply a correction thereto using correction factors; a data structure coupled to the vector modulator and including a first pair of look-up tables configured for storing amplitude and phase correction factors to compensate for amplitude and phase non-linearities in the responses of both the RF power amplifier and the vector modulator and a second pair of look-up tables configured for storing correction factors to compensate for memory effects in the response of the RF power amplifier; a circuit configured to transfer scaling factors into the data structure, the data structure configured to calculate correction factors for storage in the second pair of look-up tables from the scaling factors based on a polynomial. - View Dependent Claims (11, 12, 13, 14)
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15. An amplifier system, the system comprising:
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an RF power amplifier; and a predistorter coupled to the RF power amplifier, the predistorter comprising; a vector modulator configured to receive an RF input signal and apply a correction thereto using correction factors; a data structure coupled to the vector modulator and storing the correction factors; the data structure including a first pair of look-up tables configured for storing amplitude and phase correction factors, the correction factors of the first pair of look-up tables compensating for amplitude and phase non-linearities in the response of both the RF power amplifier and the modulator; the data structure further including a second pair of look-up tables configured for storing correction factors to compensate for memory effects in the response of the RF power amplifier. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
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24. An amplifier system, the system comprising:
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an RF power amplifier; and a predistorter coupled to the RF power amplifier, the predistorter comprising; a vector modulator configured to receive an RF input signal and apply a correction thereto using correction factors; a data structure coupled to the vector modulator and including a first pair of look-up tables configured for storing amplitude and phase correction factors to compensate for amplitude and chase non-linearities in the responses of both the RF power amplifier and the vector modulator and a second pair of look-up tables configured for storing correction factors to compensate for memory effects in the response of the RF power amplifier; a circuit further configured to transfer scaling factors into the data structure, the data structure configured to calculate correction factors for storage in the second pair of look-up tables from the scaling factors based on a polynomial. - View Dependent Claims (25, 26, 27, 28)
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29. A circuit for use in a predistorter having first and second pairs of look-up tables, the circuit comprising:
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a subtracter coupled to the first and second pairs of look-up tables and configured to subtract a previous correction factor from the second pair of look-up tables from a current correction factor from the first pair of look-up tables; a first delay circuit coupled intermediate the second pair of look-up tables and the subtracter and configured to delay correction factors from the second pair of look up tables; a second delay circuit coupled to the subtracter and configured to delay the difference between the current and previous correction factors; and a summer coupled to the second delay circuit and the second pair of look-up tables and configured to add the difference between the current and previous correction factors to a subsequent correction factor to arrive at a correction factor that is used to compensate for memory effects in an RF power amplifier.
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30. A data structure for use with an RF power amplifier comprising:
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a first look-up table for storing correction factors that correct for amplitude and phase non-linearities in the RF power amplifier; a second look-up table for storing correction factors that correct for memory effects in the RF power amplifier; the data structure including a circuit configured to receive scaling factors, the circuit further configured to use the received scaling factors and a polynomial to calculate the correction factors within the data structure and populate the look-up tables. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A method of calibrating an amplifier system, the method comprising:
loading correction factors that correct for amplitude and phase non-linearities in the response of both an RE power amplifier and a modulator into a data structure, including transferring a scaling factor into the data structure and calculating, in the data structure, correction factors that correct for memory effects in the response of an RF power amplifier from the scaling factor and a polynomial. - View Dependent Claims (43, 44)
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45. A method of predistorting a signal applied to an RF power amplifier, the method comprising:
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storing, in a first pair of look-up tables in a data structure, correction factors that correct for non-linearities in the response of both an RF power amplifier and a vector modulator; calculating, in the data structure, correction factors that correct for memory effects in the response of the RF power amplifier and storing the correction factors in a second pair of look-up tables; receiving an RF input signal using the vector modulator; sampling a portion of the RF input signal power; selecting correction factors from the data structure based on a portion of the RF input signal; and applying the correction factors to the RF input signal using the vector modulator. - View Dependent Claims (46, 47, 48, 49, 50)
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Specification