Pulse or digital communications – Transmitters – Antinoise or distortion
Reexamination Certificate
2005-08-09
2005-08-09
Liu, Shuwang (Department: 2634)
Pulse or digital communications
Transmitters
Antinoise or distortion
C375S285000, C375S295000, C375S297000, C330S149000, C445S060000
Reexamination Certificate
active
06928122
ABSTRACT:
An adaptive predistortion linearization system includes input path digital-to-analog converters (DACs), error path DACs, a digital signal processor, and a radio frequency (RF) combiner. The digital signal processor includes a look-up table storing complex gain coefficient values. The digital signal processor generates an error signal based on the complex input signal and the complex gain coefficients by using a vector decomposition calculation. Feedback from a power amplifier can be provided to a training algorithm for periodically updating the gain coefficient values stored in the look-up table. By performing separate D/A conversions, the error path and input signals can be separately filtered. This separation also permits the error signal to be decoupled from the complex input signal, which facilitates an improvement in the wide-frequency-offset noise performance of the system.
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An article entitled “Amplifier Linearization Using a Digital Predistorter with Fast Adaptation and Low Memory Requirements” by James K. Cavers, taken from IEEE Transactions on Vehicular Technology, vol. 39, No. 4, Nov. 1990, pp. 374-382.
An article entitled “A Linearizing Predistorter With Fast Adaptation” by James K. Cavers, Communications Science Laboratory, School of Engineering Science, Simon Fraser University, 1990 IEEE, pp. 41-47.
An article entitled “Adaptive Linearization Using Predistortion—Experimental Results” by Michael Faulkner, Member, IEEE, and Mats Johansson, Student Member, IEEE, taken from IEEE Transactions on Vehicular Technology, vol. 43, No. 2, May 1994, pp. 323-332.
Khan Andrew M.
Opas George F.
Palandech Robert
Liu Shuwang
Motorola Inc.
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