Integrated Frequency Synthesis for Convergent Wireless Solutions

196 Pages·2012·4.46 MB·English

by  Jad G. Atallah, Mohammed Ismail (auth.)

Analog Circuits and Signal Processing
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Jad G. Atallah (cid:129) Mohammed Ismail
Integrated Frequency
Synthesis for Convergent
Wireless Solutions
Jad G. Atallah Mohammed Ismail
Notre Dame University - Louaize The Ohio State University
Zouk Mosbeh Columbus, OH, USA
Lebanon Currently with Khalifa University, UAE
ISBN 978-1-4614-1465-0 ISBN 978-1-4614-1466-7 (eBook)
DOI 10.1007/978-1-4614-1466-7
Springer New York Heidelberg Dordrecht London
Library of Congress Control Number: 2012936297
© Springer Science+Business Media New York 2012
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To my wife, Nora, and our son, Liam
Jad G. Atallah
To the memory of my parents, my father,
Ismail Elnaggar, and my mother, Sameha
Elsharkawi
Mohammed Ismail
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Preface and Acknowledgments

Wireless transceivers combining several standards in one unit are of key impor-
tance. In order to reach the ultimate goal of maximizing the performance-to-cost
ratio of such modules, a careful study of the target application, the architecture, and
the frequency planning is strongly required. One of the most challenging tasks is the
implementation of the frequency synthesizer. This challenge is compounded by the
traditional technical dif fi culties in designing frequency synthesizers as well as the
new requirements that include multi-standard support.
As a result, studying the upper layers of the communication system becomes
mandatory in order to frame the requirements of the frequency synthesizer and to
provide a viable solution from a user’s perspective for an always-best-connected
scenario. Additionally, the study of the upper layers opens up new opportunities for
innovation at the lower layers, especially at the physical layer where the view is
traditionally restricted by certain harsh requirements whose source might not be
clear at least to the physical-level designer.
The fi rst aim of this work is to provide a holistic view of how an optimum user
experience can be achieved and how this affects the design of frequency synthesiz-
ers for the next generation networks. The work is heavily based on the existing
variety of wireless standards, although it can also serve for other applications, such
as real software-de fi ned radios and dynamic spectrum allocation.
As a result, this work cuts a vertical path starting from the best user experience
vision down to the physical layer, where it expands on the design of the frequency
synthesizer. It proposes a wireless front-end solution that can make the vision of an
always-best-connected scenario a reality. The architecture is based on a wireless
detector called Sniffer that searches for an alternative connection while the main
connection is running. Not only is the Sniffer solution viable at the physical
level, but it also acts as a stepping stone for development toward fully-enabled
multi-standard transceivers.
After this, and in line with the previous vision, some important frequency syn-
thesizer parameters are pointed out and enhancements on the phase-locked architec-
tures are presented. These include ways to extend the range of the frequency
vii
viii Preface and Acknowledgments
synthesizer and ways to make the synthesizer adaptable depending on the require-
ments of the wireless standards.
This work leads directly to the implementation of a multi-standard frequency
synthesizer, where the details of the top–down design procedure are presented at
several levels of abstraction. In order to round up the work, and due to the fact that
the requirements of the frequency synthesizer stretch thin the capabilities of the
technology used, calibration techniques to increase the yield of such a complicated
sub-system are presented, an important step toward fi rst-pass success.
Chapter 1 consists of the introductory material for the book. It sets the pace for
the overall work and provides highlights of the important points that should be kept
in mind while reading the following chapters, particularly the different contribu-
tions that the work entails. It does not try by any means to explain in detail anything
related to the work itself, since this is done in the following chapters.
Chapter 2 starts by discussing the current situation of wireless transceivers and
the role that a frequency synthesizer plays in these systems. This is followed by the
main fi gures of merit of frequency synthesizers so that they are kept in focus while
studying the upper layers of the OSI model. One of the main roles of this upper-
layer study is to motivate the need for multi-standard wireless solutions from a
practical perspective.
Chapter 3 introduces the wireless convergence challenge from a very high per-
spective and presents a background study involving a solution, which in itself is an
established standard. Afterward, the Sniffer-based architecture is introduced as a
generic and innovative solution for any combination of standards. Therefore, this
chapter contains the background study and the proposed solution, which is the fi rst
contribution of this work.
Chapter 4 applies the Sniffer architecture to the most common standards, thus
deriving the main steps that a mobile device should go through when performing the
vertical handover between them. The aim of this is to verify the practicality of the
Sniffer solution as well as to extract the most important parameters for the fre-
quency synthesizers in this situation. Therefore, this chapter consists of the continu-
ation of the fi rst contribution of the work.
Chapter 5 shifts the focus toward the frequency synthesizer. It presents a back-
ground study of the implementation options of frequency synthesizers and focuses
on the PLL architecture with a description of its components in detail.
Chapter 6 presents in detail two enhancement techniques based on traditional
phase-locked loop architectures in order to meet the various requirements of differ-
ent standards. The techniques mainly focus on the locking speed, the phase noise,
and the frequency range of frequency synthesizers. These metrics are targeted since
they are very relevant to the proposed Sniffer solution at the present time. As a
result, this chapter covers contributions two and three of the work.
Chapter 7 continues with the PLL enhancements contribution. Any multi-standard
frequency synthesizer will have a certain amount of programmability due to the
different requirements of different standards. Our circuit-based implementations
have shown that charge-pump programmability in particular might give rise to charge-
pump output non-idealities that adversely affect the phase noise of the synthesizer.
Preface and Acknowledgments ix
As a result, this chapter tries to fi nd the optimum S D M architecture given a certain
amount of charge-pump non-ideality. This constitutes the fourth contribution of
the work.
Chapter 8 presents a case study of a design of a multi-standard frequency synthe-
sizer. The chapter focuses on the design phases from the system level, including the
speci fi cations of the standards, down to the block level. This chapter covers part of
the fi fth contribution of this work, especially the design methodology used.
Chapter 9 continues with the implementation of the multi-standard frequency
synthesizer from the circuit level down to silicon. The intricacies of the design that
set it apart from other designs are pointed out along with the results. This completes
the fi fth contribution of the work.
Chapter 10 tackles the calibration topic and how it can be applied to RF systems
in general and PLLs in particular. The topic is very important considering the varia-
tions that might adversely affect the performance of the PLL and, thus, the yield of
the designs. In view of the process variations encountered when designing the syn-
thesizer, a case study is presented regarding also charge-pump non-idealities and
how to detect and correct them in a closed-loop manner. This covers the sixth and
fi nal contribution of the work.
Chapter 11 concludes the work with some hints on future directions for further
development.
This book is intended for communication systems designers as well as radio and
mixed–signal integrated circuits designers; graduate students in electrical, com-
puter, and communications engineering; as well as marketing and product managers
of wireless solutions.
This book has its roots in the Ph.D. thesis work of the fi rst author , Dr. Jad G.
Atallah, which was completed in 2008. We would like to thank all the current and
former members of the Radio and Mixed Signal Integrated Systems (RaMSiS)
group at the Royal Institute of Technology (KTH), Sweden; the Swedish Foundation
for Strategic Research (SSF); the Swedish Research Council (Vetenskapsrådet);
Notre Dame University - Louaize (NDU), Lebanon; The Ohio State University,
USA; and the Khalifa University of Science, Technology and Research (KUSTAR),
United Arab Emirates for making this work possible.
Jad G. Atallah
Mohammed Ismail
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