Amplifier predistortion and autocalibration method and apparatus
First Claim
1. An apparatus for calibrating a predistortion module, the apparatus comprising:
- means for generating a calibration signal;
means for amplifying the calibration signal based in part on a value of an envelope signal to generate an amplified calibration signal;
means for transmitting the amplified calibration signal;
means for coupling a transmit signal that comprises the amplified calibration signal to a receive signal path;
means for generating a distortion characteristic by comparing a received signal sample with the calibration signal; and
means for storing the distortion characteristic in a look up table of the predistortion module to calibrate the predistortion module.
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Accused Products
Abstract
Methods and apparatus for amplifier AM and PM predistortion and autocalibration. AM and PM amplifier distortion can be corrected using predistortion. The AM and PM distortion characteristics of the amplifier are determined using an autocalibration technique. The amplifier characteristics can be stored in distinct look up tables. Alternatively, the inverse of the amplifier characteristics can be stored in distinct look up tables. Signals that are to be amplified are characterized in polar format having a phase component with a normalized magnitude and a magnitude component. The phase component can be predistorted by applying the inverse of the PM distortion characteristics to the signal. Similarly, the magnitude component can be predistorted by applying the inverse of the AM distortion characteristics to the signal. The predistorted phase component can be amplified using the previously characterized amplifier. The predistorted magnitude component can be used to set the gain of the previously characterized amplifier.
24 Citations
15 Claims
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1. An apparatus for calibrating a predistortion module, the apparatus comprising:
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means for generating a calibration signal; means for amplifying the calibration signal based in part on a value of an envelope signal to generate an amplified calibration signal; means for transmitting the amplified calibration signal; means for coupling a transmit signal that comprises the amplified calibration signal to a receive signal path; means for generating a distortion characteristic by comparing a received signal sample with the calibration signal; and means for storing the distortion characteristic in a look up table of the predistortion module to calibrate the predistortion module. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for calibrating a predistortion module, comprising:
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a waveform generator that generates a calibration signal; a power amplifier that amplifies the calibration signal based in part on a value of an envelope signal to generate an amplified calibration signal; an antenna that transmits the amplified calibration signal; a coupler that couples a transmit signal that comprises the amplified calibration signal to a receive signal path; and a processor that generates a distortion characteristic by comparing a received signal sample with the calibration signal and store the distortion characteristic in a look-up table of the predistortion module to calibrate the predistortion module. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method for calibrating a predistortion module, comprising:
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generating a calibration signal; amplifying the calibration signal based in part on a value of an envelope signal to generate an amplified calibration signal; transmitting the amplified calibration signal; coupling a transmit signal that comprises the amplified calibration signal to a receive signal path; generating a distortion characteristic by comparing the received signal sample with the calibration signal; and storing the distortion characteristic in a look up table of the predistortion module to calibrate the predistortion module. - View Dependent Claims (13, 14, 15)
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Specification