THE UNIVERSITY OF CALGARY A Logarithmic Amplifier and Hilbert Transformer for Optical Single ...

215 Pages·2005·8.71 MB·English

THE UNIVERSITY OF CALGARY
A Logarithmic Ampli(cid:12)er and Hilbert Transformer
for Optical Single Sideband
by
Christopher Daniel Holdenried
A THESIS
SUBMITTED TO THE FACULTY OF GRADUATE STUDIES
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
DEPARTMENT OF ELECTRICAL AND COMPUTER
ENGINEERING
CALGARY, ALBERTA
February, 2005
(cid:13)c Christopher Daniel Holdenried 2005
THE UNIVERSITY OF CALGARY
FACULTY OF GRADUATE STUDIES

The undersigned certify that they have read, and recommend to the Faculty of Graduate
Studies for acceptance, a thesis entitled “A Logarithmic Amplifier and Hilbert
Transformer for Optical Single Sideband” submitted by Christopher Daniel Holdenried in
partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY.

__________________________________________
Supervisor, Dr. James W. Haslett
Department of Electrical and Computer Engineering

__________________________________________
Dr. John G. McRory
Department of Electrical and Computer Engineering

__________________________________________
Dr. Robert J. Davies
Department of Electrical and Computer Engineering

__________________________________________
Dr. Brent Maundy
Department of Electrical and Computer Engineering

__________________________________________
Dr. Harvey Yarranton
Department of Chemical and Petroleum Engineering

__________________________________________
External Examiner, Dr. Calvin Plett
Department of Electronics, Carleton University

___________________________
Date
ii
Abstract
Chromatic dispersion is the pulse spreading that occurs during transmission
through optical (cid:12)ber and is due to the non-constant delay of (cid:12)ber with wavelength.
Gigabit optical communication systems require some method of dispersion compen-
sation. Optical single sideband (OSSB) is commonly used to transmit narrow-band
signals in order to avoid power fading due to dispersion. However, in the absence
of special optical (cid:12)lters, a broadband Hilbert transformer and logarithmic ampli-
(cid:12)er are required in order to generate OSSB for baseband gigabit data signals. This
thesis describes the development of unique gigabit logarithmic ampli(cid:12)er and Hilbert
transformer integrated circuits.
The Cherry-Hooper ampli(cid:12)er with emitter follower feedback is introduced as a
gigabitampli(cid:12)erbuildingblock. Thiscircuitisultimatelyusedtodesignabroadband
logarithmic ampli(cid:12)er for OSSB. The log ampli(cid:12)er architecture is developed using a
novel design procedure, with proof of a logarithmic response. A Hilbert transformer
integrated circuit is developed based on non-integrated Hilbert transformer designs
by previous researchers. It uses Q-enhanced on-chip LC transmission lines. The log
ampli(cid:12)er and Hilbert transformer designs were fabricated as integrated circuits, and
their performance is veri(cid:12)ed through measurements of the circuits.
Simulation results of an OSSB system are described and show that the above
mentionedcircuitsenableanOSSBsystemwithimmunitytodispersive powerfading.
Actual OSSB transmitters were assembled and measured OSSB optical spectra are
presented for 5 and 10 Gb/s broadband signals and a 1.9 GHz narrow-band signal.
iii
Acknowledgements
I thank Jim Haslett for his superb guidance and sound judgement. I would not
have applied for and won certain awards without his encouragement. Thank you for
helping with designs and the long and productive hours spent writing and editing
articles. He was often able to see core mathematical ideas when I could not. I am
also grateful for his generosity which was demonstrated, for example, by allowing
me to attend conferences very early in my studies. This allowed me to see close up
what was expected of me and how to obtain it.
Thank you to John McRory for teaching me everything I know about microwave
circuits and for help designing the logarithmic ampli(cid:12)er. I thank him for negotiating
access to the NT35 technology at Nortel so that we could fabricate the (cid:12)rst loga-
rithmic ampli(cid:12)er. I also gratefully acknowledge the (cid:12)nancial support of TRLabs,
including the perks, made possible by John McRory, Roger Pederson, and George
Squires.
Thank you to Bob Davies for guidance with all of the optical communications
aspects of this thesis, and for the idea of this thesis. Thank you to the great minds
who are part of the TRLabs and ATIPS teams for many useful discussions and for
providing a challenging environment. Thank you to Dave Clegg and Chris Haugen
for assistance with experiments and equipment. Thank you to Bogdan Georgescu
for your hard work developing the coupled inductor Q-enhancement principles which
helpedmetodesigntheintegratedHilberttransformer. ThankyoutoMichaelLynch
for many useful discussions, work related and otherwise.
Thank you to A.J. Bergsma and Douglas Beards for their support and design
iv
ideas when designing the (cid:12)rst logarithmic ampli(cid:12)er. Thank you to A.J. for teaching
me about IC layout and for working late some nights to (cid:12)nish the IC layout of the
(cid:12)rstlogarithmicampli(cid:12)er. ThankyoutoNortelfor(cid:12)nancialsupportandforallowing
me to work with A.J. and Doug.
Thank you to the Canadian Microelectronics Corporation for paying for the fab-
rication of several ICs that are part of this thesis, for providing access to world class
design software, and for donating test equipment. Without this support I would
never have been able to obtain the results that I did.
I gratefully acknowledge the (cid:12)nancial support of NSERC, Alberta iCORE, and
the IEEE. Without this support, my studies would have been cut short. I value the
many friends that I have made through these organizations.
Thank you to Leila Southwood, Pauline Cummings, Simon Arsenault, and Ella
Gee for their administrative support which makes this work possible. Thanks also
to Jonathan Eskritt, Paul Horbal, and Josh Nakaska for keeping the ATIPS system
and web site going when they weren’t busy with their own research. Behind every
strong researcher, there are even stronger administrators.
v
For Regina and Siddhartha.
Thank you for love and support.
vi
Table of Contents
Approval Page ii
Abstract iii
Acknowledgements iv
Dedication vi
Table of Contents vii
List of Tables x
List of Figures xi
List Of Symbols and Abbreviations xvi
1 Introduction 1
1.1 Research Objective and Scope . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Thesis Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Background 6
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Chromatic Dispersion . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.1 Types of Dispersion . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.2 Mathematical De(cid:12)nition of Dispersion . . . . . . . . . . . . . 8
2.3 Methods to Compensate for Dispersion . . . . . . . . . . . . . . . . . 9
2.3.1 Optical Techniques . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3.2 Post Detection Compensation . . . . . . . . . . . . . . . . . . 12
2.4 Compatible Optical Single Sideband . . . . . . . . . . . . . . . . . . 14
2.4.1 Complex Envelope Representation of Bandpass Signals . . . . 14
2.4.2 COSSB Modulation . . . . . . . . . . . . . . . . . . . . . . . . 17
2.4.3 COSSB Implementation: The Ideal Minimum Phase Modula-
tor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.4.4 Dispersion E(cid:11)ects on Double and Single Sideband Signals . . 21
2.4.5 Minimum Phase Dispersion Compensation . . . . . . . . . . . 26
2.4.6 Previous Experiments Using COSSB . . . . . . . . . . . . . . 27
2.4.7 The Mach-Zehnder Modulator . . . . . . . . . . . . . . . . . . 29
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2.4.8 Competing Technologies: Solitons, Coherent Detection Sys-
tems, and Duobinary Transmission . . . . . . . . . . . . . . . 31
2.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3 Analysis and Design of HBT Cherry-Hooper Ampli(cid:12)ers with Emit-
ter Follower Feedback for Optical Communications 36
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.2 Large Signal Performance . . . . . . . . . . . . . . . . . . . . . . . . 38
3.2.1 HBT (cid:12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3 Small Signal Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 40
3.3.1 Design Example . . . . . . . . . . . . . . . . . . . . . . . . . 44
3.4 Ampli(cid:12)er Noise Performance . . . . . . . . . . . . . . . . . . . . . . 47
3.5 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4 A Novel Parallel Summation Logarithmic Ampli(cid:12)er 55
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.2 Distinction and Comparison of Logarithmic Ampli(cid:12)ers . . . . . . . . 56
4.2.1 The Series Linear-Limit Logarithmic Ampli(cid:12)er . . . . . . . . 57
4.2.2 Parallel Summation Logarithmic Ampli(cid:12)ers . . . . . . . . . . 59
4.3 Design Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.3.1 Logarithmic Slope and Intercept . . . . . . . . . . . . . . . . . 68
4.3.2 The Delay Matched Progressive Compression Ampli(cid:12)er . . . . 69
4.4 Implementation 1: A DC-4 GHz Si BJT Logarithmic Ampli(cid:12)er . . . 70
4.4.1 Design of Implementation 1 . . . . . . . . . . . . . . . . . . . 70
4.4.2 Measurements of Implementation 1 . . . . . . . . . . . . . . . 73
4.5 Implementation 2: A DC-6 GHz SiGe HBT Logarithmic Ampli(cid:12)er . 80
4.5.1 Design of Implementation 2 . . . . . . . . . . . . . . . . . . . 80
4.5.2 Measurements of Implementation 2 . . . . . . . . . . . . . . . 87
4.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
5 A 10 Gb/s Hilbert Transformer with Q-Enhanced LC Transmission
Lines 92
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
5.2 HT Transfer Function. . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.3 Design of LC Transmission Lines . . . . . . . . . . . . . . . . . . . . 96
5.3.1 Q-Enhanced LC Transmission Lines . . . . . . . . . . . . . . . 97
5.4 Circuit Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . 101
5.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
viii
6 Simulations of COSSB System Implementations 116
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
6.2 Performance of the Logarithmic Ampli(cid:12)er . . . . . . . . . . . . . . . 116
6.3 Performance of the HT . . . . . . . . . . . . . . . . . . . . . . . . . 121
6.4 Combined Performance of Logarithmic Ampli(cid:12)er and HT Circuits . . 125
6.4.1 Performance at a Mach-Zehnder Modulation Depth of 0.25 . 125
6.4.2 Performance at a Mach-Zehnder Modulation Depth of 0.20 . 133
6.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
7 Measurements of COSSB Transmitters 140
7.1 10 Gb/s COSSB Experiment Using the HT . . . . . . . . . . . . . . 140
7.2 COSSB Experiments Using the HT and the Logarithmic Ampli(cid:12)er . . 145
7.2.1 Experiment Using a 1.9 GHz Sinusoid . . . . . . . . . . . . . 145
7.2.2 Experiment Using Filtered 5 Gb/s Data . . . . . . . . . . . . 147
7.3 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
8 Conclusions 155
8.0.1 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Bibliography 160
A Ampli(cid:12)er DC Transfer Characteristic 167
B Analysis of the Emitter Follower Load 169
C Derivation of Equation (3.11) 171
D Example Calculation of an Ampli(cid:12)er Noise Contribution 172
E Widlar Biasing 174
F Design of the Logarithmic Ampli(cid:12)er Test Fixture 178
G Description of Equipment Used for COSSB Experiments 182
ix
List of Tables
3.1 Di(cid:11)erential output noise of the CHEF ampli(cid:12)er at 1 GHz. . . . . . . 49
4.1 Comparison of high frequency true log ampli(cid:12)ers. . . . . . . . . . . . 90
5.1 Noise (cid:12)gure of HT die C with Q-enhancement turned on. . . . . . . . 109
G.1 List of major equipment used in COSSB experiments. . . . . . . . . . 183
G.2 Power characteristic of the Sumitomo intensity modulator. . . . . . . 190
x