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Sampling requirements for nonlinear basis waveforms used in digital predistortion and amplifier modeling

Published online by Cambridge University Press:  18 February 2013

R. Neil Braithwaite
R. Neil Braithwaite*
Affiliation:
Powerwave Technologies, 1801 E. St. Andrew Place, Santa Ana, CA 92705, USA
*
Corresponding author: R. Neil Braithwaite Email: nbraithwaite@pwav.com
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Abstract

Power amplifier (PA) nonlinearities and the digital predistortion (DPD) required for linearization are modeled at baseband using the memoryless polynomial, memory polynomial, and pruned Volterra series. The sampling requirements for the nonlinear basis waveforms created from a band-limited signal are determined as a function of the polynomial order. A Gaussian approximation of the channel filtering is used to make the mathematical analysis tractable. For the memory polynomial and pruned Volterra series cases, the spacing between memory taps, referred to as the delay offset, is selected to trade off model accuracy and the condition number of the coefficient estimation. Examples are provided showing how to select the appropriate delay offset for a memory-based amplifier model and its effect on the DPD performance. A pruned Volterra series is proposed, which demonstrates improved DPD performance compared with the memory polynomial.

Keywords

Power amplifiers and linearizersModellingSimulation and characterizations of devices and circuits
Type
Research Papers
Information
International Journal of Microwave and Wireless Technologies , Volume 5 , Special Issue 2: Special Issue on Power Amplifier Linearization , April 2013 , pp. 103 - 113
Copyright
Copyright © Cambridge University Press and the European Microwave Association 2013

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References

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