Microwave Power Oscillator utilizing Thin-Film Ferroelectic Varactors by Alan M. Victor A ...

473 Pages·2010·30.78 MB·English

Microwave Power Oscillator utilizing Thin-Film Ferroelectic Varactors
by
Alan M. Victor
A dissertation submitted to the Graduate Faculty of
North Carolina State University
in partial fulfillment of the
requirements for the Degree of
Doctor of Philosophy
Electrical Engineering
Raleigh, North Carolina
2010
APPROVED BY:
Dr. Paul Franzon Dr. Jon-Paul Maria
Dr. David Schurig Dr. Michael B. Steer
Chair of Advisory Committee
(cid:13)c Copyright 2010 by Alan M. Victor
All Rights Reserved
ABSTRACT
VICTOR, ALAN M. Microwave Power Oscillator utilizing Thin-Film Ferroelectic Varactors.
(Under the direction of Dr. Michael B. Steer.)
Microwavecommunicationsystemsdemandsimplifiedandefficientpoint-to-pointandpoint-
to-multi-pointlinks. ThisresearchfocusesondirectRF(radiofrequency)carriergenerationand
architectures to support microwave systems utilizing this technique. Direct carrier frequency
generation relies on the synthesis of power oscillators operating efficiently at the final output
frequency. Power oscillators in this work permit a stable tunable frequency source with output
power greater than 1 watt with modulation capability. Improvement in operating efficiency or
the conversion of DC input power into RF microwave signals requires devices operating with
high breakdown voltage. The high breakdown voltage feature removes the need for wasteful
conversion of available high DC input supply voltages to lower operating voltages via voltage
regulation or DC-to-DC conversion. The combination of appropriate RF architecture, analysis
techniques, and device technology are investigated to maximize operating efficiency. In this
work, the effort is focused on the capabilities of Gallium Nitride on Silicon (Si-GaN) HFET
coupled with Barium Strontium Titanate (BST) thin-film varactors.
Studiesareconfinedtoanoperatingfrequencyrangeof1–6GHz. Oscillatordesignisimple-
mented via a synthesis technique and is achieved by combining the procedure of active device
mapping with large signal circuit analysis. The outcome of a portion of this work identifies
a routine of “tuning” the active device reflection coefficient to effectively absorb parasitics as-
sociated with hybrid oscillator implementation. Emphasis is primarily on output power, RF
conversion and load efficiencies, and tuning bandwidth. Oscillator load efficiency is approached
via the application of describing functions for non linear operation. Nonlinear descriptions are
general so both the FET and the bipolar device share similar expressions for load efficiency.
Conversion efficiency must contend with thin-film varactor Q, which is also addressed. The
development of high power sources with wide tuning bandwidth while maintaining adequate
phasenoisealsorequirestechnologywithhighbreakdownvoltage. Inthiswork,phasenoiseand
tuning bandwidth are related to physical factors which describe the varactor. Networks which
permit favorable tradeoff in tunability and power efficiency are discussed. The characteristics
of GaN on Silicon and of BST varactors, components that both have demonstrated high break-
down voltage, are investigated. The tracking phase lock characteristic of an oscillator using
a BST varactor is unique and revealed in this study. Distinguishing the noise mechanism in
oscillators incorporating BST varactors is addressed. The study of noise in BST is investigated
at baseband and then applied to power oscillator design. Studies of small signal oscillators with
output power less than 100 mW and operation below 1 GHz provides important design insight.
These studies assess the impact that a varactor with large breakdown voltage has on noise, on
linearity of the oscillator tuning frequency characteristics, without the abberations caused by
having a large RF signal. Furthermore, oscillator operation at lower frequencies also permits
the study of large RF excitation voltages when present and impressed across the varactor. The
alteration of oscillator performance is readily observed, as the affect of circuit parasitics are
less.
Although circuit function and device characteristics are the central part of this work, it is
essential that the integration of a system perspective be included. Power oscillators are part of
an RF system and a new radio architecture design resulting in improved RF power conversion
efficiency which is presented. In this work a phase lock methodology is used to implement a
power oscillator directly operating at the carrier frequency. This direct carrier launch method
is contrasted with the traditional heterodyne architecture. For both cases, a methodology for
optimizing the signal-to-noise ratio of a cascade transmitter system using what is called an
equal contribution methodology is presented. This method is also applied to receive systems.
The approach readily determines the offending network or networks in the RF system and also
provides an approach for optimization of system dynamic range.
DEDICATION
First and foremost, I want to dedicate this work to my family. Particularly my wife and her
kitchentable, whichImonopolizedformanyyearsincompletingthiswork. Thankyou, Phyllis,
for forcing me to continue to work towards this goal. I want to thank my family, my son Todd,
mydaughterLynda, mydaughter-in-law, Heather, andournewestmember, mygrand-daughter
Madeline, for their patience. There were many hours spent away from them, working on this
project. However, I knew quite early on, this dissertation was not going to write itself. If there
were a way to place it on auto pilot, I would have!
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BIOGRAPHY
Alan Victor received the B.S.E.E. degree from the University of Florida, Gainesville and the
M.S.E. degree from Florida Atlantic University, Boca Raton. After graduation he joined the
Motorola Communications Group working in research and development, and was a senior staff
engineer. He received several patents in circuits and systems relating to the two-way radio
industry. Following Motorola he co-founded a wireless radio LAN company providing data
communications equipment to the auto ID industry. Subsequently he was at IBM, and then the
Nitronex corporation investigating Silicon Germanium and Gallium Nitride on Silicon circuits
for radio systems targeting the personnel communications industry. While at IBM, he began
work towards the Ph.D. degree at North Carolina State University, Raleigh. During that same
period, he joined Harris Microwave Division as a Senior Scientist where he was involved with
microwave transceiver design. His main interests are low noise circuits, power oscillators, and
the application of ferroelectric materials. Mr. Victor is a member of Eta Kappa Nu and a
senior member of the IEEE.
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ACKNOWLEDGEMENTS
There are numerous colleagues who I have worked with over the years at Motorola, IBM,
Harris Microwave, Nitronex Corporation, and at North Carolina State University. To each of
them, thank you for being mentors, and for allowing me to mentor. I would like to thank my
committee members, Dr. Barlarge, Dr. Franzon, Dr. Gard, Dr. Kingon, Dr. J.-P. Maria, Dr.
Schurig, and Dr. Steer for their guidance and inputs. Particularly to Dr. Steer, thank you
for the guidance and continued push to see this work through and for providing me with an
excellent “sounding” board in order to bounce off some crazy ideas.
My coauthors who assisted in all this work and participated in the various published papers
and conference proceedings, to all of you, I thank you. In particular, Dr. Jayesh Nath, who
not only was a fine person to mentor, but is a great mentor himself.
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TABLE OF CONTENTS
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Chapter 1 Introduction and Motivation . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Architecture overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 System analysis tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3 Direct carrier launch system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.5 Original Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Chapter 2 Investigation of Architectural and Specific Circuit Functions . . . 23
2.1 The problem definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2 Heterodyne and homodyne approaches and concerns . . . . . . . . . . . . . . . . 24
2.3 Network noise analysis: introduction to AM, PM and pure noise . . . . . . . . . 28
2.3.1 The amplifier noise model . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.3.2 Frequency translator noise model, mixer and variations . . . . . . . . . . 35
2.3.3 Noise analysis in systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
2.3.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
2.3.5 Phase lock multiplier introduction . . . . . . . . . . . . . . . . . . . . . . 48
2.3.6 Phase lock multiplier architecture . . . . . . . . . . . . . . . . . . . . . . 49
2.3.7 Reduction of spurious signals in a wide band loop . . . . . . . . . . . . . 56
2.4 Phase lock multiplier operation with modulation . . . . . . . . . . . . . . . . . . 62
2.4.1 Power transfer oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
2.5 Power oscillator development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
2.5.1 Oscillator-power amplifier, a review of the interface . . . . . . . . . . . . . 69
2.5.2 Active device-resonator interaction and tunability . . . . . . . . . . . . . 79
2.6 A resonator-device interface for improved phase noise. . . . . . . . . . . . . . . . 87
2.7 Conclusions and summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Chapter 3 Alternative Architectures, Circuit Topologies, and Related Work . 100
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
3.1.1 Overviewofspecifictechniquesstudied...alternativestodirectcarriergen-
eration transmit function . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
3.2 GMSK constant phase modulators by reference multiplication . . . . . . . . . . . 103
3.3 Injection locked oscillators and pulse-injection locking . . . . . . . . . . . . . . . 105
3.4 Parallel locking of multiple sources . . . . . . . . . . . . . . . . . . . . . . . . . . 105
3.5 Offset phase lock loops and sampling (SPD) phase detectors . . . . . . . . . . . . 106
3.6 Direct conversion transmitters (DCT) . . . . . . . . . . . . . . . . . . . . . . . . 107
3.7 Wideband phase locking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
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3.8 Polar modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
3.9 Summary of related approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Chapter 4 Theory of Systems, Power Oscillator Synthesis, and Components . 110
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
4.2 Overview of theoretical discussions . . . . . . . . . . . . . . . . . . . . . . . . . . 111
4.3 Systems architecture design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
4.3.1 Transceiver cascade system synthesis via an equal contribution method . 113
4.4 Oscillator synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
4.4.1 The conditions for sustained oscillation . . . . . . . . . . . . . . . . . . . 123
4.4.2 Oscillator tuning synthesis via termination mapping and maximum in-
stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
4.4.3 The conditions for sustained oscillation . . . . . . . . . . . . . . . . . . . 135
4.4.4 Device mapping and modification . . . . . . . . . . . . . . . . . . . . . . . 141
4.4.5 The mechanics of mapping applied to oscillator synthesis . . . . . . . . . 151
4.4.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
4.4.7 Co-design techniques using EM-Harmonic balance applied to hybrid VCOs154
4.4.8 Resonator loaded Q in oscillators, the complex Q, and active Q measure-
ment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
4.4.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
4.5 Oscillator load efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
4.5.1 Closed loop-to-open loop oscillator model . . . . . . . . . . . . . . . . . . 176
4.5.2 Oscillator load efficiency analysis . . . . . . . . . . . . . . . . . . . . . . . 180
4.6 BST based voltage tuned oscillators . . . . . . . . . . . . . . . . . . . . . . . . . 186
4.6.1 Properties of BST VCO in tracking phase lock loop . . . . . . . . . . . . 188
4.6.2 Phase noise characterization of a BST based oscillator . . . . . . . . . . . 198
4.6.3 Excess varactor noise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212
4.6.4 Conclusions on excess noise in BST varactor . . . . . . . . . . . . . . . . 217
4.6.5 BST Oscillator tuning gain, linearity and stability . . . . . . . . . . . . . 220
4.6.6 Definition of tuning linearity and tuning gain . . . . . . . . . . . . . . . . 221
4.6.7 Uniqueness of BST applied to linear tuning . . . . . . . . . . . . . . . . . 226
4.6.8 Experiment, observation and data . . . . . . . . . . . . . . . . . . . . . . 229
4.6.9 The reduction of tuning gain due to varactor leakage . . . . . . . . . . . . 236
4.6.10 Summary and conclusions of this section . . . . . . . . . . . . . . . . . . . 240
4.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Chapter 5 Implementation of Circuits and Systems . . . . . . . . . . . . . . . . . 245
5.1 Overview of circuit implementations . . . . . . . . . . . . . . . . . . . . . . . . . 245
5.1.1 Negative resistance IMFET and GaN power oscillators . . . . . . . . . . . 246
5.1.2 Design overview and summary . . . . . . . . . . . . . . . . . . . . . . . . 261
5.1.3 Reflection coefficient shaping . . . . . . . . . . . . . . . . . . . . . . . . . 265
5.1.4 Tracking phase lock loop with BST . . . . . . . . . . . . . . . . . . . . . . 274
5.1.5 Mechanically Induced Modulation . . . . . . . . . . . . . . . . . . . . . . 282
5.2 Summary of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286
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Chapter 6 Case studies, Power Oscillators and System Optimization . . . . . . 288
6.1 Highlights of the case studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289
6.1.1 One port negative reflection coefficient vs. PA closed loop power oscillator290
6.1.2 Addressing a reflection coefficient problem . . . . . . . . . . . . . . . . . . 299
6.1.3 Conclusions on resonator and active device interface . . . . . . . . . . . . 307
6.2 GaN and IMFET power oscillators from power amplifiers . . . . . . . . . . . . . 308
6.2.1 Si-GaN HFET power oscillator efficiency . . . . . . . . . . . . . . . . . . . 324
6.3 Maximizing RF system dynamic range . . . . . . . . . . . . . . . . . . . . . . . . 330
6.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 347
Chapter 7 Applied Measurements and Theory to Noise and Components . . . 349
7.1 Characterization of varactor Q and C ... addressing a measurement problem . . . 350
7.2 Special techniques applied to noise measurements of two ports . . . . . . . . . . 369
7.3 Special techniques applied to the noise measurements of sources . . . . . . . . . . 376
7.4 Conclusions and summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383
Chapter 8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 384
Chapter 9 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407
Appendix A PhaseNoiseMeasurementsfromLowFrequencyHumandNoiseMeasure 408
Appendix B Excess Noise in Varactors . . . . . . . . . . . . . . . . . . . . . . . . . . 415
Appendix C Mapping Analysis Applied to Oscillator Synthesis . . . . . . . . . . . . 418
Appendix D DC-RF Load-Conversion Efficiency in FET Oscillators . . . . . . . . . 429
Appendix E Spurious Free Dynamic Range . . . . . . . . . . . . . . . . . . . . . . . 441
Appendix F Oscillator Equivalent Input Noise . . . . . . . . . . . . . . . . . . . . . 444
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