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Model order selection for digital predistortion of a RF power amplifier when the distortion spectrum exceeds the observation bandwidth

Published online by Cambridge University Press:  26 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

Digital predistortion (DPD) of a nonlinear power amplifier (PA) is made challenging when the observation bandwidth (OBW) used to measure the output signal is narrower than the intermodulation distortion (IMD) spectrum generated. Wide bandwidth input signals stimulate memory effects within the PA thereby requiring the model order of the DPD to be expanded to include memory correction coefficients. However, if the model order is over-specified relative to the OBW, the estimation of the DPD coefficients will be ill-conditioned and the distortion cancellation will be degraded. This paper proposes a method of selecting the best model order of the DPD coefficient estimation for the available OBW. Adjacent channel power ratio (ACPR) is used as an independent measure of the distortion cancellation for a given model order. Experimental results demonstrate the relationship between the model order of the estimation, the OBW, and the ACPR performance of the wide bandwidth IMD cancellation.

Keywords

amplifier distortioncommunication system nonlinearitiespower amplifier linearization
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. 163 - 170
Copyright
Copyright © Cambridge University Press and the European Microwave Association 2013

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References

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