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by Stephen James Grant, In The School, Stephen J. Grant, Simon Fraser University
http://www.ensc.sfu.ca/people/grad/grantq/personal/pubs/masc_thesis.pdf
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Abstract:
ii Currently, the only available wideband (multiple MHz), accurate, amplifier linearization method is feedforward. Feedforward, though, requires automatic adaptation of key parameters for reliable distortion cancellation as operational and environmental conditions vary. In this thesis, previous analysis on adaptive feedforward linearization is extended to include an alternative placement of the adaptive signal cancellation coefficient. In contrast to previous analysis, this placement results in a non-quadratic error surface. Consequently, two available criteria for the optimization of the signal cancellation coefficient result in different optimal values. This result can have practical implementation consequences under certain operating conditions. A new analysis is presented that shows that various inaccuracies in the implementation of baseband correlation, such as frequency and phase offsets, filter mismatches, and incomplete image suppression, do not affect the final converged coefficient values. With a novel and appropriate use of DSP, a feedforward linearizer has been implemented with adaptation driven by easily computed
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