Surface Acoustic Wave Devices in Telecommunications: Modelling and Simulation

338 Pages·2000·11.77 MB·English

by  Professor Ken-ya Hashimoto (auth.)

Ken-ya Hashimoto
Surface Acoustic Wave Devices in Telecommunications
Springer-Verlag Berlin Heidelberg GmbH
ONLINE LIBRARY
http://www.springer.de/engine/
Ken-ya Hashimoto
Surface Acoustic
Wave Devices
in Telecommunications
Modelling and Simulation
With 330 Figures
i
Springer
Professor Ken-ya Hashimoto
Chiba University
Faculty of Engineering
Department of Electronics & Mechanical Engineering
1-33 Yayoi-cho, Inage-ku
263-8522 Chiba
Japan
E-mail: [e-mail]
Library of Congress Cataloging-in-Publication Data applied for.
Die Deutsche Bibliothek -CIP-Einheitsaufnahme
Hashimoto, Ken-ya: Surface acoustic wave devices in telecommunications: modelling and simulationl
Ken-ya Hashimoto.
ISBN 978-3-642-08659-5 ISBN 978-3-662-04223-6 (eBook)
DOI 10.1007/978-3-662-04223-6
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© Springer-Verlag Berlin Heidelberg 2000
Originally published by Springer-Verlag Berlin Heidelberg New York in 2000
Softcover reprint of the hardcover lst edition 2000
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Preface
Although the existence of the surface acoustic wave (SAW) was first dis
cussed in 1885 by Lord Rayleigh [1], it did not receive engineering interest
for a long time. In 1965, the situation changed dramatically. White suggested
that SAWs can be excited and detected efficiently by using an interdigital
transducer (IDT) placed on a piezoelectric substrate [2]. This is because very
fine IDTs can be mass-produced by using photolithography, which has been
well developed for semiconductor device fabrication, and proper design of the
IDT enables the construction of transversal filters with outstanding perfor
mance.
Then, in Europe and America, a vast amount of effort was invested in the
research and development of SAW devices for military and communication
uses, such as delay lines and pulse compression filters for radar and highly
stable resonators for clock generation. Research activities are reflected in the
various technical papers represented by special issues [3-5] and proceedings
[6]. The establishment of design and fabrication technologies and the rapid
growth of digital technologies, represented by the microcomputer, meant that
the importance of SAW devices for the military decreased year by year and
most researchers in national institutions and universities left this field after
reductions or cuts in their financial support. Then the end of the Cold War
forced many SAW researchers in companies to do so, too.
On the other hand, Japanese researchers also paid much attention to
SAW devices from the 1960s, but were mainly concerned with consumer and
communication applications. Starting with intermediate-frequency (IF) filters
for TVs [7], various filters and resonators were developed and mass-produced
from the mid-1970s. After that, though, many companies left the competition
because of price reductions and fixed market shares. The same reasons forced
even successful companies to shrink their research sections. So Japanese re
search activities were diminished until the mid-1980s.
Rapid growth of the mobile communication market in the late 1980s
changed the situation again. Many new-comers joined the surviving com
panies and very tight competition was restarted [8]. In Japan, more than 20
companies produce SAW devices now. The expanded market also stimulated
research activities, and much innovative work has emerged in the last 10
years.
VI Preface
Through the development, the previous disadvantages of SAW devices,
such as large insertion loss and low power durability, have been overcome.
SAW devices have already been applied even to antenna duplexer of mobile
phones, whose requirements are extremely severe.
In addition, until very recently, researchers believed that the practical
frequency limit for the mass production of SAW devices is about 1 GHz.
However, very rapid progress in microfabrication technologies imported from
LSI production and in the refinement of the fabrication process enables mass
production of SAW devices in the 2.5 GHz range [9].
It is not unreasonable to expect that specifications for SAW devices will be
more stringent in conjunction with rapid advances in digital communication
technologies.
By the way, I entered the SAW field in 1977 as an undergraduate under
the supervision of Professor Yamaguchi of Chiba University, and have contin
ued my activities in the same laboratory for the last 20 years. My most recent
main subject is the development of fast and precise simulators for SAW de
vices. There are many opportunities to partake in discussions with researchers
who are interested in this work. During the discussion, they often asked me
the questions: "Are there any textbooks about the subject?" or "Where is the
discussion written up?" But, unfortunately, it is quite hard to answer them.
This is because most books related to SAWs [10-18] were published before
the rapid growth of the mobile communication market. They mainly concern
transversal filters, and few descriptions are given of the resonator-related de
vices which are now widely used. Furthermore, devices employing SH-type
SAWs and computer-based simulation technologies are scarcely detailed.
The aim here is to give an overview of the latest SAW technologies, such
as the design and simulation of resonator-based devices employing SH-type
leaky SAWs. Although the description is not highly mathematical, various
theoretical foundations inherent in the development of precise simulation and
design techniques are explained in detail.
Note that this book is not intended as a complete textbook. It is a supple
ment covering subjects not fully described in other books. From this reason,
many important technologies, such as device fabrication, packaging, evalua
tion, optimal design, etc., are not discussed in this book.
This book is written such that readers can understand the content most
easily. The explanations and descriptions are sometimes different from those
in the original papers, and are sometimes even unusual. I do not doubt that
there remain many errors and discrepancies. Any comments, questions, and
error modification will be appreciated.
Of course, most of the content of this book is not my own achievement
but is a gift of the tremendous effort of all SAW researchers around the world.
Although I doubt if I am the perfect person to write such a book, much effort
spent in the preparation has allowed me to do so.
Preface VII
The remaining original work was accomplished under collaboration with
and/or supervision by Professor Masatsune Yamaguchi of Chiba University.
Of course, I must express my special thanks to him for his support and
guidance. Tireless effort and innovative ideas came from the staff members
and students in our laboratory. Without their support, we could achieve
nothing.
In addition, I must express my special thanks to Prof. Robert Weigel of
Universitiit Linz who strongly suggested I publish this book and who kindly
introduced me to Dr. Merkle of Springer-Verlag. Publication of this book
would have been impossible without their understanding and encouragement.
I would like to thank all Japanese SAW researchers, represented by Profes
sor Emeritus Kimio Shibayama of Tohoku University and Professor Yasutaka
Shimizu of Tokyo Institute of Technology for their guidance and support. In
addition, I appreciate many friends all over the world. Fruitful discussions
and comments with them provided stimulation and encouragement.
Among them, I gratefully acknowledge Dr. Yoshio Sato of Fujitsu Labo
ratories, Inc., Mr. Hideki Omori and Mr. Yoshiro Fujiwara of Fujitsu Media
Device Limited, Mr. Akihiro Bungo of Mitsubishi Materical Co. Ltd., and
Dr. Clemens Ruppel of Siemens Corporate Technology for supplying much of
the experimental data used in this book.
It is my great pleasure to express my special thanks to the following three
persons. The late Professor Hiroshi Shimizu of Tohoku University showed
me how university researchers should be. Dr. Fred Cho of Motorola Inc.
encouraged me from an early stage of my career and trained me to survive in
this world. Mr. Clinton Hartmann of RF SAW Components, Inc. is teaching
me to be a true engineer. Discussions with him were always severe, but a lot of
new innovative ideas came through them as a gift of his immense knowledge
and experience. Thanks again.
Finally I thank my parents, my wife Kaoru and my daughter Hirono for
their tireless support, encouragement and understanding.
Chiba University, January 2000 }(en-ya llashi~oto
References
1. L. Rayleigh: On Waves Propagating along the Plane Surface of an Elastic Solid,
Proc. London Math. Soc., 7 (1885) pp. 4-11.
2. R.M. White and F.W. Voltmer: Direct Piezoelectric Coupling to Surface Elastic
Waves, Appl. Phys. Lett., 17 (1965) pp. 314-316.
3. T.M. Reeder (ed.): Special Issue on Microwave Acoustic Signal Processing,
IEEE Trans. Microwave Theory and Tech., MTT-21, 4 (1973).
4. L. Claiborne, G.S. Kino and E. Stern (eds): Special Issue on Surface Acoustic
Wave Devices and Applications, Proc. IEEE, 64, 5 (1976).
5. R.C. Williamson and T.W. Bristol (eds): Special Issue on Surface-Acoustic
Wave Applications, IEEE Trans. Sonics and Ultrason., SU-28, 2 (1981).
6. E.A. Ash and E.G.S. Paige (eds): Rayleigh-Wave Theory and Application,
Springer-Verg, New York (1985).
7. S. Takahashi, H. Hirano, T. Kodama, F. Miyashiro, B. Suzuki, A. Onoe, T.
Adachi and K. Fujinuma: SAW IF Filter on LiTa03 for Color TV Receivers,
IEEE Trans. Consumer Electron., CE-24, 3 (1978) pp. 337-346.
8. K. Shibayama and K. Yamanouchi (eds): Proc. International Symp. on Surface
Acoustic Wave Devices for Mobile Communication (1992).
9. T. Matsuda, H. Uchishiba, 0. Ikata, T. Nishihara andY. Satoh: LandS band
Low-Loss Filters Using SAW Resonators, Proc. IEEE Ultrason. Symp. (1994)
pp. 163-167.
10. B.A. Auld: Acoustic Waves and Fields in Solids, Vol. I & II, Wiley, New York
(1973).
11. H. Matthews (ed): Surface Wave Filters, Wiley, New York (1977).
12. D.P. Morgan: Surface-Wave Devices for Signal Processing, Elsevier, Amsterdam
(1985).
13. E.A. Gerber and A. Ballato (eds): Precision Frequency Control, Vol. I & II,
Academic Press, Orlando (1985).
14. S. Datta: Surface Acoustic Wave Devices, Prentice Hall, Englewood Cliffs
(1986). .
15. G.S. Kino: Acoustic Waves: Devices, Imaging, & Analog Signal Processing,
Prentice-Hall, Englewood Cliffs (1987}.
16. C.K. Campbell: Surface Acoustic Wave Devices and Their Signal Processing
Applications, Academic Press, Boston (1989).
17. C.K. Campbell: Surface Acoustic Wave Devices for Mobile and Wireless Com
munication, Academic Press, Boston (1998).
18. M. Feldmann and J. Henaff: Surface Acoustic Waves for Signal Processing,
Altech House, Boston (1989}.
Contents
1. Bulk Acoustic and Surface Acoustic Waves . . . . . . . . . . . . . . . 1
1.1 Bulk Acoustic Waves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.1 Elastic Waves in Solids.. . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1.2 Wavevector and Group Velocity . . . . . . . . . . . . . . . . . . . . 4
1.1.3 Behavior of BAWs at a Boundary . . . . . . . . . . . . . . . . . . 6
1.1.4 Diffraction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.1.5 Piezoelectricity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.1.6 Evanescent Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.1.7 Waveguides...................................... 12
1.1.8 Behavior at the Boundary Between Waveguides . . . . . . 13
1.1.9 Open Waveguides .... , . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2 Waves in a Semi-infinite Substrate . . . . . . . . . . . . . . . . . . . . . . . . 17
1.2.1 Excitation of L-and SV-type Waves . . . . . . . . . . . . . . . . 17
1.2.2 Excitation of SH-type Waves. . . . . . . . . . . . . . . . . . . . . . . 18
1.2.3 Leaky SAWs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
1.2.4 Leaky and Nonleaky SAWs . . . . . . . . . . . . . . . . . . . . . . . . 21
1.2.5 SSBW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2. Grating. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.1 Basic Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.1.1 Fundamentals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.1.2 Reflection Center... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.2 Behavior in Periodic Structures . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2.1 Bragg Reflection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2.2 Energy Storing Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.2.3 Fabry-Perot Resonator. . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2.3 Equivalent Circuit Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.3.1 Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.3.2 Dependence of Reflection Characteristics on Parameters 35
2.4 Metallic Grating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
2.4.1 Fundamental Characteristics....................... 39
2.4.2 SAW Dispersion Characteristics.................... 40
2.4.3 Approximated Dispersion Characteristics............ 42
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
X Contents
3. Interdigital Transducers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
3.1.1 Bidirectional IDTs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 7
3.1.2 Unidirectional IDTs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
3.2 Static Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.2.1 Charge Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
3.2.2 Electromechanical Coupling Factor . . . . . . . . . . . . . . . . . 53
3.2.3 Element Factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.2.4 Complex Electrode Geometries . . . . . . . . . . . . . . . . . . . . . 56
3.2.5 Effect of IDT Ends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.3 IDT Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.3.1 Delta-Function Model............................. 61
3.3.2 Equivalent Circuit Model . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3.3.3 Other Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
3.4 Influence of Peripheral Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.4.1 Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.4.2 Smith Chart and Impedance Matching . . . . . . . . . . . . . . 70
3.4.3 Achievable Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
3.5 p Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.5.1 Summary... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.5.2 IDT Characterization by Using p Matrix . . . . . . . . . . . . 76
3.5.3 Discussion on Unidirectional IDTs.................. 77
3.6 BAW Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.6.1 Phase Matching Condition......................... 79
3.6.2 Radiation Characteristics... . . . . . . . . . . . . . . . . . . . . . . . 81
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
4. Transversal Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.1 Basics..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.1.1 Weighting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.1.2 Basic Properties of Weighted IDTs . . . . . . . . . . . . . . . . . 91
4.1.3 Effects of Peripheral Circuits. . . . . . . . . . . . . . . . . . . . . . . 92
4.2 Design of Transversal Filters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
4.2.1 Fourier Transforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
4.2.2 Remez Exchange Method .......................... 100
4.2.3 Linear Programming .............................. 101
4.3 Spurious Responses ..................................... 103
4.3.1 Diffraction ....................................... 103
4.3.2 Bulk Waves ...................................... 107
4.3.3 Other Parasitic Effects ............................ 110
4.4 Low-Loss Transversal Filters ............................. 112
4.4.1 Multi-IDT Structures ............................. 112
4.4.2 Transversal Filters Employing SPUDTs ............. 114
4.4.3 Combination of SPUDTs and Reflectors . . . . . . . . . . . . . 117
References ................................................. 120