Digital Predistortion of Power Amplifiers
for Wireless Applications
A Thesis
Presented to
The Academic Faculty
by
Lei Ding
In Partial Fulfillment
of the Requirements for the Degree
Doctor of Philosophy
School of Electrical and Computer Engineering
Georgia Institute of Technology
March 2004
Digital Predistortion of Power Amplifiers
for Wireless Applications
Approved by:
Dr. G. Tong Zhou, Advisor
Dr. J. Stevenson Kenney
Dr. W. Marshall Leach
Dr. Ye (Geoffrey) Li
Dr. Jianmin Qu
Date Approved: April 1, 2004
For my family.
iii
ACKNOWLEDGEMENTS
It is time to draw a period to my PhD endeavor. I feel extremely lucky to meet so many
talented people during these years. I am grateful for their friendship, help, encouragement,
and support.
First, I would like to thank my advisor, Dr. G. Tong Zhou, for providing this opportunity
for me to study at Georgia Tech. Her constant encouragement and valuable advices are
essential for the completion of this thesis. I will be always inspired by the high standards
she sets for herself and her sharp focus and deep devotion to whatever she works on.
I would like to thank my thesis committee members: Drs. J. Stevenson Kenney, W.
Marshall Leach, Ye (Geoffrey) Li, and Jianmin Qu for taking time to serve on my committee
and for their questions and suggestions. My special thanks also go to Drs. Monson Hayes
and Douglas B. Williams for the excellent classes they offered, which benefit me a lot for
my research work and job search.
I also benefit a lot from my two summer internships at Bell Labs, Lucent Technologies.
I would like to thank Drs. Zhengxiang Ma and Dennis R. Morgan for making this possible.
I enjoyed every aspect of my internship experience: talented colleagues, excellent research
opportunities, cool weather, nice work environment, and the list goes on. My special thanks
also go to Dr. Yiteng Huang for his friendship and help during my stay in New Jersey.
I would li ke to thank my group members: Yongsub, Krishna, Muhammad, Raviv, Gail,
Ning, Hua, Chunpeng, Yuan, Thao, Vincent, and Bob for all the technical discussions and
help along the way. I also enjoyed interactions with the nice Chinese student community
here at CSIP.
A lot of credit goes to my parents. Their unconditional supp ort has always helped me
in all my endeavors. I would also like to thank my sister for her support and feeding me
with great dishes from time to time. Last but not least, I would like to thank my wife,
wenjin, for her love, encouragement, and support.
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TABLE OF CONTENTS
Dedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Chapter 2 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Modeling Memoryless Power Amplifiers . . . . . . . . . . . . . . . . . 5
2.2 Predistortion of Memoryless Power Amplifier . . . . . . . . . . . . . . 7
2.2.1 Data Predistortion for Memoryless Power Amplifiers . . . . . 7
2.2.2 Signal Predistortion for Memoryless Power Amplifiers . . . . . 8
2.3 Modeling Power Amplifiers with Memory Effects . . . . . . . . . . . . 10
2.4 Predistortion of Power Amplifiers with Memory Effects . . . . . . . . 14
Chapter 3 Digital Predistorter Design . . . . . . . . . . . . . . . . . . . . . 17
3.1 Hammerstein Pre distorter Design . . . . . . . . . . . . . . . . . . . . 17
3.1.1 Hammerstein Predistorter Training . . . . . . . . . . . . . . . 17
3.1.2 Hammerstein Predistorter Simulation . . . . . . . . . . . . . . 22
3.2 Memory Polynomial Predistorter Design . . . . . . . . . . . . . . . . 25
3.2.1 Memory Polynomial Predistorter Training . . . . . . . . . . . 25
3.2.2 Memory Polynomial Predistorter Simulation . . . . . . . . . . 26
3.2.3 Memory Polynomial Predistorter Discussion . . . . . . . . . . 33
3.3 A New Combined Predistorter Design . . . . . . . . . . . . . . . . . . 35
3.3.1 Combined Predistorter Model . . . . . . . . . . . . . . . . . . 36
3.3.2 Combined Predistorter Training . . . . . . . . . . . . . . . . . 37
3.3.3 Effects of Noise and Initial Estimates . . . . . . . . . . . . . . 40
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