Table Of ContentACSP · Analog Circuits And Signal Processing
S. Mahdi Kashmiri
Kofi A.A. Makinwa
Electrothermal
Frequency
References in
Standard CMOS
Electrothermal Frequency References
in Standard CMOS
ANALOG CIRCUITS AND SIGNAL PROCESSING
Series Editors:
Mohammed Ismail, The Ohio State University
Mohamad Sawan, Polytechnique Montreal
For further volumes:
http://www.springer.com/series/7381
S. Mahdi Kashmiri • Kofi A.A. Makinwa
Electrothermal Frequency
References in Standard
CMOS
S. Mahdi Kashmiri Kofi A.A. Makinwa
Texas Instruments, Inc. Delft University of Technology
Delftechpark 19 Delft, The Netherlands
Delft, The Netherlands
ISBN 978-1-4614-6472-3 ISBN 978-1-4614-6473-0 (eBook)
DOI 10.1007/978-1-4614-6473-0
Springer New York Heidelberg Dordrecht London
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Acknowledgment
The original manuscript of this book was written as a Ph.D. thesis at
Delft University of Technology, where I spent about five fruitful years. This
Ph.D. journey would not have been possible without the support of many people,
to whom I would like to express my gratitude.
At the foremost, I thank my supervisor Kofi Makinwa. Throughout years, Kofi’s
belief, enthusiasm and presence was a solid supporting force, which helped me go
on. I learnt from him to be as critical as I can, and how to write and to present such
that others can actually understand! I am thankful to him for these lifelong skills.
I also thank Han Huijsing for his support and encouragement. I would like to thank
Michiel Pertijs for his invaluable support with the design of the first reference’s
temperature compensation.
I need to thank Omid Shoaei from Tehran University, who first raised the passion
for analog circuit design in me. He told us, his students, about the glory of writing
to the red journal and about being fired if the company misses time-to-market due
to design mistakes. It all seemed so exciting!
Academic experience during the Ph.D. research is extremely valuable. I am
thankful to Marcel Pelgrom and Lucien Breems for the opportunity of assisting
them within their data converter design courses at TU Delft.
I would like to thank Greta Milczanowska and Marc van Eylen from
Europractice, IMEC, for their support with the manufacture of 0.7 μm chips.
I express my gratitude to Frank Thus, Paul Noten and Erik Moderegger for their
invaluable support and NXP Semiconductors for fabrication of the scaled electro-
thermal frequency references in 0.16 μm CMOS.
I am thankful to the wonderful room-mates at the electrical engineering faculty
of TU Delft, with whom I shared lots of memories. In a chronological order: Andre´
Aita, Lukas Mol, Ferran Reverter, Caspar van Vroonhoven, Luca Giangrande,
Saleh Heidary, and Zichao Tan. Caspar worked on thermal-diffusivity-based tem-
perature sensors, which is why we enjoyed lots of fruitful discussions, technology
and experience sharing, as well as a wonderful camping trip to New Zealand.
v
vi Acknowledgment
Special thanks to the staff of the Electronic Instrumentation (EI) lab of TU Delft,
whose valuable work allows the department to run. During my times Inge, Trudie,
Pia, Helly, Ilse and Joyce ran the secretary office. Thanks to Willem van der Sluys
who made it financially feasible. Thanks to the technical staff Ger, Piet, Jeroen,
Maureen, and Zu-Yao Chang. Thanks to Antoon Frehe who took care of the servers
and made designing possible.
And of course, many friends and colleague whose presence in my life has
meant a lot to me. In an alphabetical order: Arvin Emadi, Berenice, ChungKai
Yang, Dafina Tanase, Eduardo Margallo, Frerik Witte, Gayathri, Gregory
Pandraud, Kamran Souri, Lukasz, Martijn Snoeij, Morteza Alavi, Mohammad
Talaie, Mohammad Mehrmohammadi, Mohammad Farazian, M. Nabavi, Nishant,
Omid Noroozian, Pedram Khalili, Paulo Silva, Qinwen Fan, Rong Wu, Sha,
Sharma, Shishir, Ugur, Wen Wu, Youngcheol Che, Yue Chen and Zili. Also thanks
to the wonderful remote colleagues at NXP: Fabio Sebastiano and Mohammed
Bolatkale.
Thanks to Sarah von Galambos for English corrections of the original Ph.D.
thesis draft.
The preparation of the original thesis draft took one and half year during which
I combined working and writing. This would not have been possible without
the support of my colleagues at the precision systems group of Texas Instruments
Delft design center (former National Semiconductor). I am especially thankful
to my manager Wilko Kindt. I am also thankful to my colleagues: Frerik Witte,
Jinju Wang, and Sergio Roche.
I am very much indebted to my family, my parents and my brothers, for their
support and trust in me. It is thanks to their dedications and love that I have been
able to pursue my dreams. Thanks to all of you.
And last but not the least: I am indefinitely thankful to my fiance´e, Esme´e.
Without her unconditional love, understanding, and support I would not have
finished this book.
Delft, The Netherlands S. Mahdi Kashmiri
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Frequency and Its Accuracy Measures . . . . . . . . . . . . . . . . . . . . 1
1.2 Challenge of Integrating Frequency References . . . . . . . . . . . . . 4
1.3 Frequency Generation Based on the Thermal
Properties of Silicon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
1.5 Challenges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.6 Organization of the Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Silicon-Based Frequency References . . . . . . . . . . . . . . . . . . . . . . . . 15
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.2 Silicon MEMS Based Oscillators . . . . . . . . . . . . . . . . . . . . . . . . 17
2.3 LC Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.4 RC Harmonic Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.5 RC Relaxation Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.6 Ring Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.6.1 Open-Loop Compensation . . . . . . . . . . . . . . . . . . . . . . . 31
2.6.2 Closed-Loop Compensation . . . . . . . . . . . . . . . . . . . . . . 32
2.7 Mobility-Based Frequency References . . . . . . . . . . . . . . . . . . . . 36
2.8 Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
2.9 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3 Frequency References Based on the Thermal
Properties of Silicon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.2 Thermal Properties of Silicon . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.3 Electrothermal Filters in CMOS . . . . . . . . . . . . . . . . . . . . . . . . 51
vii
viii Contents
3.4 ETF Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3.4.1 General Heater Considerations . . . . . . . . . . . . . . . . . . 55
3.4.2 General Thermopile Considerations . . . . . . . . . . . . . . 55
3.4.3 Design of a Bar ETF . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.4.4 Design of an Optimized ETF . . . . . . . . . . . . . . . . . . . 58
3.5 Modeling for Time-Domain Analysis . . . . . . . . . . . . . . . . . . . . 60
3.6 Thermal Oscillators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
3.7 Electrothermal Frequency-Locked Loops . . . . . . . . . . . . . . . . . 64
3.8 Electrothermal FLL as Foundation
for Frequency References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
3.9 Dynamics of an Electrothermal FLL . . . . . . . . . . . . . . . . . . . . 70
3.10 FLL Behavioral Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . 75
3.11 The Effect of Noise on an FLL’s Jitter . . . . . . . . . . . . . . . . . . . 78
3.11.1 ETF Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
3.11.2 Implications for FLL Design . . . . . . . . . . . . . . . . . . . . 80
3.11.3 VCO Noise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
3.12 Challenges Associated with the Previous FLL’s . . . . . . . . . . . . 83
3.13 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
4 A Digitally-Assisted Electrothermal Frequency-Locked
Loop in Standard CMOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
4.2 Proposing a Digitally-Assisted FLL . . . . . . . . . . . . . . . . . . . . . 89
4.2.1 Operating Principle . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.2.2 DAFLL System-Level Specifications . . . . . . . . . . . . . . 90
4.2.3 DAFLL Realization Phases . . . . . . . . . . . . . . . . . . . . . 91
4.3 First Test Chip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
4.3.1 PDΔΣM System-Level Architecture . . . . . . . . . . . . . . 92
4.3.2 PDΔΣM Circuit Design . . . . . . . . . . . . . . . . . . . . . . . 98
4.3.3 First Chip Experimental Results . . . . . . . . . . . . . . . . . 107
4.3.4 Conclusions from the First Test Chip . . . . . . . . . . . . . 110
4.4 Second Test Chip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
4.4.1 DCO System-Level Architecture . . . . . . . . . . . . . . . . . 112
4.4.2 Complete DAFLL System-Level Simulations . . . . . . . 112
4.4.3 DCO Circuit Design . . . . . . . . . . . . . . . . . . . . . . . . . . 115
4.4.4 Experimental Results with the Second Test Chip . . . . . 118
4.5 Measuring the Effective Thermal-Diffusivity
of CMOS Chips Using a DAFLL . . . . . . . . . . . . . . . . . . . . . . . 120
4.5.1 The Essence of Measuring Deff . . . . . . . . . . . . . . . . . . 121
4.5.2 Thermal Diffusivity Measurement Using
CMOS ETFs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
Contents ix
4.5.3 An Electrothermal FLL as a Test
Vehicle in Measuring Deff . . . . . . . . . . . . . . . . . . . . . . . 123
4.5.4 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
4.6 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
5 An Electrothermal Frequency Reference
in Standard 0.7 μm CMOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
5.2 Temperature Compensation of Electrothermal
Frequency-Locked Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
5.3 Realization of an Electrothermal Frequency
Reference in a 0.7 μm CMOS Process . . . . . . . . . . . . . . . . . . . . 134
5.3.1 System-Level Design of the Reference . . . . . . . . . . . . . . 134
5.3.2 The Band-Gap Temperature Sensor Design . . . . . . . . . . . 137
5.3.3 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
5.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
6 A Scaled Electrothermal Frequency Reference
in Standard 0.16 μm CMOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
6.2 Scaling Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
6.3 System-Level Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
6.4 Error Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
6.5 Circuit Realizations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
6.5.1 ETF and PDΔΣM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
6.5.2 DCO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
6.5.3 Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
6.5.4 Heater Drive Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . 176
6.6 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
6.7 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184
7 Conclusions and Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
7.1 Main Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
7.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
About the Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
