9 research outputs found
Analysis and Design of Silicon based Integrated Circuits for Radio Frequency Identification and Ranging Systems at 24GHz and 60GHz Frequency Bands
This scientific research work presents the analysis and design of radio frequency (RF) integrated circuits (ICs) designed for two cooperative RF identification (RFID) proof of concept systems. The first system concept is based on localizable and sensor-enabled superregenerative transponders (SRTs) interrogated using a 24GHz linear frequency modulated continuous wave (LFMCW) secondary radar. The second system concept focuses on low power components for a 60GHz continuous wave (CW) integrated single antenna frontend for interrogating close range passive backscatter transponders (PBTs).
In the 24GHz localizable SRT based system, a LFMCW interrogating radar sends a RF chirp signal to interrogate SRTs based on custom superregenerative amplifier (SRA) ICs. The SRTs receive the chirp and transmit it back with phase coherent amplification. The distance to the SRTs are then estimated using the round trip time of flight method. Joint data transfer from the SRT to the interrogator is enabled by a novel SRA quench frequency shift keying (SQ-FSK) based low data rate simplex communication. The SRTs are also designed to be roll invariant using bandwidth enhanced microstrip patch antennas. Theoretical analysis is done to derive expressions as a function of system parameters including the minimum SRA gain required for attaining a defined range and equations for the maximum number of symbols that can be transmitted in data transfer mode. Analysis of the dependency of quench pulse characteristics during data transfer shows that the duty cycle has to be varied while keeping the on-time constant to reduce ranging errors. Also the worsening of ranging precision at longer distances is predicted based on the non-idealities resulting from LFMCWchirp quantization due to SRT characteristics and is corroborated by system level measurements. In order to prove the system concept and study the semiconductor technology dependent factors, variants of 24GHz SRA ICs are designed in a 130nm silicon germanium (SiGe) bipolar complementary metal oxide technology (BiCMOS) and a partially depleted silicon on insulator (SOI) technology. Among the SRA ICs designed, the SiGe-BiCMOS ICs feature a novel quench pulse shaping concept to simultaneously improve the output power and minimum detectable input power. A direct antenna drive SRA IC based on a novel stacked transistor cross-coupled oscillator topology employing this concept exhibit one of the best reported combinations of minimum detected input power level of â100 dBm and output power level of 5.6 dBm, post wirebonding. The SiGe stacked transistor with base feedback capacitance topology employed in this design is analyzed to derive parameters including the SRA loop gain for design optimization. Other theoretical contributions include the analysis of the novel integrated quench pulse shaping circuit and formulas derived for output voltage swing taking bondwire losses into account. Another SiGe design variant is the buffered antenna drive SRA IC having a measured minimum detected input power level better than â80 dBm, and an output power level greater than 3.2 dBm after wirebonding. The two inputs and outputs of this IC also enables the design of roll invariant SRTs. Laboratory based ranging experiments done to test the concepts and theoretical considerations show a maximum measured distance of 77m while transferring data at the rate of 0.5 symbols per second using SQ-FSK. For distances less than 10m, the characterized accuracy is better than 11 cm and the precision is better than 2.4 cm. The combination of the maximum range, precision and accuracy are one of the best reported among similar works in literature to the authorâs knowledge.
In the 60GHz close range CW interrogator based system, the RF frontend transmits a continuous wave signal through the transmit path of a quasi circulator (QC) interfaced to an antenna to interrogate a PBT. The backscatter is received using the same antenna interfaced to the QC. The received signal is then amplified and downconverted for further processing. To prove this concept, two optimized QC ICs and a downconversion mixer IC are designed in a 22nm fully depleted SOI technology. The first QC is the transmission lines based QC which consumes a power of 5.4mW, operates at a frequency range from 56GHz to 64GHz and occupies an area of 0.49mm2. The transmit path loss is 5.7 dB, receive path gain is 2 dB and the tunable transmit path to receive path isolation is between 20 dB and 32 dB. The second QC is based on lumped elements, and operates in a relatively narrow bandwidth from 59.6GHz to 61.5GHz, has a gain of 8.5 dB and provides a tunable isolation better than 20 dB between the transmit and receive paths. This QC design also occupies a small area of 0.34mmÂČ while consuming 13.2mW power. The downconversion is realized using a novel folded switching stage down conversion mixer (FSSDM) topology optimized to achieve one of the best reported combination of maximum voltage conversion gain of 21.5 dB, a factor of 2.5 higher than reported state-of-the-art results, and low power consumption of 5.25mW. The design also employs a unique back-gate tunable intermediate frequency output stage using which a gain tuning range of 5.5 dB is attained. Theoretical analysis of the FSSDM topology is performed and equations for the RF input stage transconductance, bandwidth, voltage conversion gain and gain tuning are derived. A feasibility study for the components of the 60GHz integrated single antenna interrogator frontend is also performed using PBTs to prove the system design concept.:1 Introduction 1
1.1 Motivation and Related Work . . . . . . . . . . . . . . . . . . . . . 1
1.2 Scope and Functional Specifications . . . . . . . . . . . . . . . . . 4
1.3 Objectives and Structure . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Features and Fundamentals of RFIDs and Superregenerative Amplifiers 9
2.1 RFID Transponder Technology . . . . . . . . . . . . . . . . . . . . 9
2.1.1 Chipless RFID Transponders . . . . . . . . . . . . . . . . . 10
2.1.2 Semiconductor based RFID Transponders . . . . . . . . . . 11
2.1.2.1 Passive Transponders . . . . . . . . . . . . . . . . 11
2.1.2.2 Active Transponders . . . . . . . . . . . . . . . . . 13
2.2 RFID Interrogator Architectures . . . . . . . . . . . . . . . . . . . 18
2.2.1 Interferometer based Interrogator . . . . . . . . . . . . . . . 19
2.2.2 Ultra-wideband Interrogator . . . . . . . . . . . . . . . . . . 20
2.2.3 Continuous Wave Interrogators . . . . . . . . . . . . . . . . 21
2.3 Coupling Dependent Range and Operating Frequencies . . . . . . . 25
2.4 RFID Ranging Techniques . . . . . . . . . . . . . . . . . . . . . . . 28
2.4.0.1 Received Signal Strength based Ranging . . . . . 28
2.4.0.2 Phase based Ranging . . . . . . . . . . . . . . . . 30
2.4.0.3 Time based Ranging . . . . . . . . . . . . . . . . . 30
2.5 Architecture Selection for Proof of Concept Systems . . . . . . . . 32
2.6 Superregenerative Amplifier (SRA) . . . . . . . . . . . . . . . . . . 35
2.6.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.6.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . 42
2.6.3 Frequency Domain Characteristics . . . . . . . . . . . . . . 45
2.7 Semiconductor Technologies for RFIC Design . . . . . . . . . . . . 48
2.7.1 Silicon Germanium BiCMOS . . . . . . . . . . . . . . . . . 48
2.7.2 Silicon-on-Insulator . . . . . . . . . . . . . . . . . . . . . . . 48
3 24GHz Superregenerative Transponder based Identification and Rang-
ing System 51
3.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1.1 SRT Identification and Ranging . . . . . . . . . . . . . . . . 51
3.1.2 Power Link Analysis . . . . . . . . . . . . . . . . . . . . . . 55
3.1.3 Non-idealities . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.1.4 SRA Quench Frequency Shift Keying for data transfer . . . 61
3.1.5 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 63
3.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.2.1 Low Power Direct Antenna Drive CMOS SRA IC . . . . . . 66
3.2.1.1 Circuit analysis and design . . . . . . . . . . . . . 66
3.2.1.2 Characterization . . . . . . . . . . . . . . . . . . . 69
3.2.2 Direct Antenna Drive SiGe SRA ICs . . . . . . . . . . . . . 71
3.2.2.1 Stacked Transistor Cross-coupled Quenchable Oscillator
. . . . . . . . . . . . . . . . . . . . . . . . 72
3.2.2.1.1 Resonator . . . . . . . . . . . . . . . . . . 72
3.2.2.1.2 Output Network . . . . . . . . . . . . . . 75
3.2.2.1.3 Stacked Transistor Cross-coupled Pair and
Loop Gain . . . . . . . . . . . . . . . . . 77
3.2.2.2 Quench Waveform Design . . . . . . . . . . . . . . 85
3.2.2.3 Characterization . . . . . . . . . . . . . . . . . . . 89
3.2.3 Antenna Diversity SiGe SRA IC with Integrated Quench
Pulse Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.2.3.1 Circuit Analysis and Design . . . . . . . . . . . . 91
3.2.3.1.1 Crosscoupled Pair and Sampling Current 94
3.2.3.1.2 Common Base Input Stage . . . . . . . . 95
3.2.3.1.3 Cascode Output Stage . . . . . . . . . . . 96
3.2.3.1.4 Quench Pulse Shaping Circuit . . . . . . 96
3.2.3.1.5 Power Gain . . . . . . . . . . . . . . . . . 99
3.2.3.2 Characterization . . . . . . . . . . . . . . . . . . . 102
3.2.4 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 103
3.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 106
3.3.1 Superregenerative Transponders . . . . . . . . . . . . . . . 106
3.3.1.1 Bandwidth Enhanced Microstrip Patch Antennas 108
3.3.2 FMCW Radar Interrogator . . . . . . . . . . . . . . . . . . 114
3.3.3 Chirp Z-transform Based Data Analysis . . . . . . . . . . . 116
4 60GHz Single Antenna RFID Interrogator based Identification System 121
4.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
4.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.2.1 Quasi-circulator ICs . . . . . . . . . . . . . . . . . . . . . . 125
4.2.1.1 Transmission Lines based Quasi-Circulator IC . . 126
4.2.1.2 Lumped Elements WPD based Quasi-Circulator . 130
4.2.1.3 Characterization . . . . . . . . . . . . . . . . . . . 134
4.2.1.4 Knowledge Gained . . . . . . . . . . . . . . . . . . 135
4.2.2 Folded Switching Stage Downconversion Mixer IC . . . . . 138
4.2.2.1 FSSDM Circuit Design . . . . . . . . . . . . . . . 138
4.2.2.2 Cascode Transconductance Stage . . . . . . . . . . 138
4.2.2.3 Folded Switching Stage with LC DC Feed . . . . . 142
4.2.2.4 LO Balun . . . . . . . . . . . . . . . . . . . . . . . 145
4.2.2.5 Backgate Tunable IF Stage and Offset Correction 146
4.2.2.6 Voltage Conversion Gain . . . . . . . . . . . . . . 147
4.2.2.7 Characterization . . . . . . . . . . . . . . . . . . . 150
4.2.2.8 Knowledge Gained . . . . . . . . . . . . . . . . . . 151
4.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 154
5 Experimental Tests 157
5.1 24GHz System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
5.1.1 Ranging Experiments . . . . . . . . . . . . . . . . . . . . . 157
5.1.2 Roll Invariance Experiments . . . . . . . . . . . . . . . . . . 158
5.1.3 Joint Ranging and Data Transfer Experiments . . . . . . . 158
5.2 60GHz System Detection Experiments . . . . . . . . . . . . . . . . 165
6 Summary and Future Work 167
Appendices 171
A Derivation of Parameters for CB Amplifier with Base Feedback Capac-
itance 173
B Definitions 177
C 24GHz Experiment Setups 179
D 60 GHz Experiment Setups 183
References 185
List of Original Publications 203
List of Abbreviations 207
List of Symbols 213
List of Figures 215
List of Tables 223
Curriculum Vitae 22
Development of Scale and Rotation Invariant Neural Network based Technique for Detection of Dielectric Contrast Concealed Targets with Millimeter Wave System
The detection of concealed targets beneath a personâs clothing from standoff distance is an important task for protection and the security of a person in a crowded place like shopping malls, airports and playground stadium, etc. The detection capability of the concealed weapon depends on a lot of factors likes, a collection of back scattered data, dielectric property and a thickness of covering cloths, the hidden object, standoff distance and the probability of false alarm owing to objectionable substances. Though active millimeter wave systems have used to detect weapons under cloths, but still more attention is required to detect the target likes a gun, knife, and matchbox. To observe such problems, active V-band (59 GHz- 61 GHz) MMW radar with the help of artificial neural network (ANN) has been demonstrated for non-metallic as well as metallic concealed target detection. To validate ANN, the signature of predefined targets is matched with the signature of validated data with the help of the correlation coefficient. The proposed technique has good capability to distinguish concealed targets under various cloths.
Compressive Sensing and Its Applications in Automotive Radar Systems
Die Entwicklung in Richtung zu autonomem Fahren verspricht, kĂŒnftig einen sicheren
Verkehr ohne tödliche UnfÀlle zu ermöglichen, indem menschliche Fahrer vollstÀndig
ersetzt werden. Dadurch entfÀllt der Faktor des menschlichen Fehlers, der aus
MĂŒdigkeit, Unachtsamkeit oder Alkoholeinfluss resultiert. Um jedoch eine breite
Akzeptanz fĂŒr autonome Fahrzeuge zu erreichen und es somit eines Tages vollstĂ€ndig
umzusetzen, sind noch eine Vielzahl von Herausforderungen zu lösen. Da in einem
autonomen Fahrzeug kein menschlicher Fahrer mehr in NotfÀllen eingreifen kann,
mĂŒssen sich autonome Fahrzeuge auf leistungsfĂ€hige und robuste Sensorsysteme
verlassen können, um in kritischen Situationen auch unter widrigen Bedingungen
angemessen reagieren zu können. Daher ist die Entwicklung von Sensorsystemen
erforderlich, die fĂŒr FunktionalitĂ€ten jenseits der aktuellen advanced driver assistance
systems eingesetzt werden können. Dies resultiert in neuen Anforderungen, die erfĂŒllt
werden mĂŒssen, um sichere und zuverlĂ€ssige autonome Fahrzeuge zu realisieren, die
weder Fahrzeuginsassen noch Passanten gefÀhrden. Radarsysteme gehören zu den
SchlĂŒsselkomponenten unter der Vielzahl der verfĂŒgbaren Sensorsysteme, da sie im
Gegensatz zu visuellen Sensoren von widrigen Wetter- und Umgebungsbedingungen
kaum beeintrĂ€chtigt werden. DarĂŒber hinaus liefern Radarsysteme zusĂ€tzliche
Umgebungsinformationen wie Abstand, Winkel und relative Geschwindigkeit zwischen
Sensor und reflektierenden Zielen. Die vorliegende Dissertation deckt im Wesentlichen
zwei Hauptaspekte der Forschung und Entwicklung auf dem Gebiet der Radarsysteme
im Automobilbereich ab. Ein Aspekt ist die Steigerung der Effizienz und Robustheit
der Signalerfassung und -verarbeitung fĂŒr die Radarperzeption. Der andere Aspekt ist
die Beschleunigung der Validierung und Verifizierung von automated cyber-physical
systems, die parallel zum Automatisierungsgrad auch eine höhere KomplexitÀt
aufweisen.
Nach der Analyse zahlreicher möglicher Compressive Sensing Methoden, die im
Bereich Fahrzeugradarsysteme angewendet werden können, wird ein rauschmoduliertes
gepulstes Radarsystem vorgestellt, das kommerzielle Fahrzeugradarsysteme in
seiner Robustheit gegenĂŒber Rauschen ĂŒbertrifft. Die Nachteile anderer gepulster
Radarsysteme hinsichtlich des Signalerfassungsaufwands und der Laufzeit werden
durch die Verwendung eines Compressive Sensing-Signalerfassungs- und Rekonstruktionsverfahrens
in Kombination mit einer Rauschmodulation deutlich verringert.
Mit Compressive Sensing konnte der Aufwand fĂŒr die Signalerfassung um 70% reduziert
werden, wĂ€hrend gleichzeitig die Robustheit der Radarwahrnehmung auch fĂŒr signal-to-noise-ratio-Pegel nahe oder unter Null erreicht wird. Mit einem validierten
Radarsensormodell wurde das Rauschradarsystem emuliert und mit einem
kommerziellen Fahrzeugradarsystem verglichen. Datengetriebene Wettermodelle
wurden entwickelt und wÀhrend der Simulation angewendet, um die Radarleistung
unter widrigen Bedingungen zu bewerten. WĂ€hrend eine BesprĂŒhung mit Wasser die
RadomdÀmpfung um 10 dB erhöht und Spritzwasser sogar um 20 dB, ergibt sich die
eigentliche Begrenzung aus der Rauschzahl und Empfindlichkeit des EmpfÀngers. Es
konnte bewiesen werden, dass das vorgeschlagene Compressive Sensing Rauschradarsystem
mit einer zusÀtzlichen SignaldÀmpfung von bis zu 60 dB umgehen kann
und damit eine hohe Robustheit in ungĂŒnstigen Umwelt- und Wetterbedingungen
aufweist.
Neben der Robustheit wird auch die Interferenz berĂŒcksichtigt. Zum einen wird
die erhöhte Störfestigkeit des Störradarsystems nachgewiesen. Auf der anderen
Seite werden die Auswirkungen auf bestehende Fahrzeugradarsysteme bewertet und
Strategien zur Minderung der Auswirkungen vorgestellt.
Die Struktur der Arbeit ist folgende. Nach der EinfĂŒhrung der Grundlagen
und Methoden fĂŒr Fahrzeugradarsysteme werden die Theorie und Metriken hinter
Compressive Sensing gezeigt. DarĂŒber hinaus werden weitere Aspekte wie Umgebungsbedingungen,
unterschiedliche Radararchitekturen und Interferenz erlÀutert.
Der Stand der Technik gibt einen Ăberblick ĂŒber Compressive Sensing-AnsĂ€tze und
Implementierungen mit einem Fokus auf Radar. DarĂŒber hinaus werden Aspekte
von Fahrzeug- und Rauschradarsystemen behandelt. Der Hauptteil beginnt mit
der Vorstellung verschiedener AnsĂ€tze zur Nutzung von Compressive Sensing fĂŒr
Fahrzeugradarsysteme, die in der Lage sind, die Erfassung und Wahrnehmung von
Radarsignalen zu verbessern oder zu erweitern. AnschlieĂend wird der Fokus auf
ein Rauschradarsystem gelegt, das mit Compressive Sensing eine effiziente Signalerfassung
und -rekonstruktion ermöglicht. Es wurde mit verschiedenen Compressive
Sensing-Metriken analysiert und in einer Proof-of-Concept-Simulation bewertet. Mit
einer Emulation des Rauschradarsystems wurde das Potential der Compressive Sensing
Signalerfassung und -verarbeitung in einem realistischeren Szenario demonstriert.
Die Entwicklung und Validierung des zugrunde liegenden Sensormodells wird ebenso
dokumentiert wie die Entwicklung der datengetriebenen Wettermodelle. Nach der
Betrachtung von Interferenz und der Koexistenz des Rauschradars mit kommerziellen
Radarsystemen schlieĂt ein letztes Kapitel mit Schlussfolgerungen und einem
Ausblick die Arbeit ab.Developments towards autonomous driving promise to lead to safer traffic, where fatal
accidents can be avoided after making human drivers obsolete and hence removing
the factor of human error. However, to ensure the acceptance of automated driving
and make it a reality one day, still a huge amount of challenges need to be solved.
With having no human supervisors, automated vehicles have to rely on capable and
robust sensor systems to ensure adequate reactions in critical situations, even during
adverse conditions. Therefore, the development of sensor systems is required that
can be applied for functionalities beyond current advanced driver assistance systems.
New requirements need to be met in order to realize safe and reliable automated
vehicles that do not harm passersby.
Radar systems belong to the key components among the variety of sensor systems.
Other than visual sensors, radar is less vulnerable towards adverse weather and
environment conditions. In addition, radar provides complementary environment
information such as target distance, angular position or relative velocity, too. The
thesis ad hand covers basically two main aspects of research and development in the
field of automotive radar systems. One aspect is to increase efficiency and robustness
in signal acquisition and processing for radar perception. The other aspect is to
accelerate validation and verification of automated cyber-physical systems that
feature more complexity along with the level of automation.
After analyzing a variety of possible Compressive Sensing methods for automotive
radar systems, a noise modulated pulsed radar system is suggested in the thesis at
hand, which outperforms commercial automotive radar systems in its robustness
towards noise. Compared to other pulsed radar systems, their drawbacks regarding
signal acquisition effort and computation run time are resolved by using noise modulation
for implementing a Compressive Sensing signal acquisition and reconstruction
method. Using Compressive Sensing, the effort in signal acquisition was reduced by
70%, while obtaining a radar perception robustness even for signal-to-noise-ratio
levels close to or below zero. With a validated radar sensor model the noise radar
was emulated and compared to a commercial automotive radar system. Data-driven
weather models were developed and applied during simulation to evaluate radar performance
in adverse conditions. While water sprinkles increase radome attenuation
by 10 dB and splash water even by 20 dB, the actual limitation comes from noise
figure and sensitivity of the receiver. The additional signal attenuation that can be
handled by the proposed compressive sensing noise radar system proved to be even up to 60 dB, which ensures a high robustness of the receiver during adverse weather
and environment conditions.
Besides robustness, interference is also considered. On the one hand the increased
robustness towards interference of the noise radar system is demonstrated. On
the other hand, the impact on existing automotive radar systems is evaluated and
strategies to mitigate the impact are presented.
The structure of the thesis is the following. After introducing basic principles
and methods for automotive radar systems, the theory and metrics of Compressive
Sensing is presented. Furthermore some particular aspects are highlighted such as
environmental conditions, different radar architectures and interference. The state of
the art provides an overview on Compressive Sensing approaches and implementations
with focus on radar. In addition, it covers automotive radar and noise radar related
aspects. The main part starts with presenting different approaches on making use
of Compressive Sensing for automotive radar systems, that are capable of either
improving or extending radar signal acquisition and perception. Afterwards the focus
is put on a noise radar system that uses Compressive Sensing for an efficient signal
acquisition and reconstruction. It was analyzed using different Compressive Sensing
metrics and evaluated in a proof-of-concept simulation. With an emulation of the
noise radar system the feasibility of the Compressive Sensing signal acquisition and
processing was demonstrated in a more realistic scenario. The development and
validation of the underlying sensor model is documented as well as the development
of the data-driven weather models. After considering interference and co-existence
with commercial radar systems, a final chapter with conclusions and an outlook
completes the work
Few-Shot User-Adaptable Radar-Based Breath Signal Sensing
Vital signs estimation provides valuable information about an individualâs overall health
status. Gathering such information usually requires wearable devices or privacy-invasive settings.
In this work, we propose a radar-based user-adaptable solution for respiratory signal prediction
while sitting at an office desk. Such an approach leads to a contact-free, privacy-friendly, and easily
adaptable system with little reference training data. Data from 24 subjects are preprocessed to extract
respiration information using a 60 GHz frequency-modulated continuous wave radar. With few
training examples, episodic optimization-based learning allows for generalization to new individuals.
Episodically, a convolutional variational autoencoder learns how to map the processed radar data
to a reference signal, generating a constrained latent space to the central respiration frequency.
Moreover, autocorrelation over recorded radar data time assesses the information corruption due to
subject motions. The model learning procedure and breathing prediction are adjusted by exploiting
the motion corruption level. Thanks to the episodic acquired knowledge, the model requires an
adaptation time of less than one and two seconds for one to five training examples, respectively. The
suggested approach represents a novel, quickly adaptable, non-contact alternative for office settings
with little user motion.ITEA3 Unleash Potentials in Simulation
(UPSIM) project (N°19006) German Federal Ministry of Education and Research
(BMBF)Austrian Research Promotion Agency (FFG)Rijksdienst voor Ondernemend Nederland
(Rvo)Innovation Fund Denmark (IFD
MEMS based radar sensor for automotive collision avoidance
This dissertation presents the architecture of a new MEMS based 77 GHz frequency modulated continuous wave (FMCW) automotive long range radar sensor. The design, modeling, and fabrication of a novel MEMS based TE10 mode Rotman lens. MEMS based Single-pole-triple-throw (SP3T) RF switches and an inset feed type microstrip antenna array that form the core components of the newly developed radar sensor. The novel silicon based Rotman lens exploits the principle of a TE10 mode rectangular waveguide that enabled to realize the lens in silicon using conventional microfabrication technique with a cavity depth of 50 Όm and a footprint area to 27 mm x 36.2 mm for 77 GHz operation. The microfabricated Rotman lens replaces the conventional microelectronics based analog or digital beamformers as used in state-of-the-art automotive long range radars to results in a smaller form-factor superior performance less complex low cost radar sensor. The developed Rotman lens has 3 beam ports, 5 array ports, 6 dummy ports and HFSS simulation exhibits better than -2 dB insertion loss and better than -20 dB return loss between the beam ports and the array ports. A MEMS based 77 GHz SP3T cantilever type RF switch with conventional ground connecting bridges (GCB) has been designed, modelled, and fabricated to sequentially switch the FMCW signal among the beam ports of the Rotman lens. A new continuous ground (CG) SP3T switch has been designed and modeled that shows a 4 dB improvement in return loss, 0.5 dB improvement in insertion loss and an isolation improvement of 3.5 dB over the conventional GCB type switch. The fabrication of the CG type switch is in progress. Both the switches have a footprint area of 500 ”m x 500 Όm. An inset feed type 77 GHz microstrip antenna array has been designed, modelled, and fabricated on a Duroid 5880 substrate using a laser ablation technique. The 12 mm x 35 mm footprint area antenna array consists of 5 sub-arrays with 12 microstrip patches in each of the sub-arrays. HFSS simulation result shows a gain of 18.3 dB, efficiency of 77% and half power beam width of 9°
The application of aperture synthesis techniques to satellite radar altimetry
Radar altimetry over the ocean is now a well established discipline of satellite remote sensing, providing measurements of mean height, significant waveheight and surface wind speed. In contrast, radar altimetry over non-ocean surfaces, to obtain topography of land and polar ice sheets, is still a new idea. The difference between these two situations is that the ocean surface is essentially flat with a very small vertical extent, so a broad-beam pulse-limited mode radar altimeter having a relatively small antenna is sufficient to give very accurate measurements of the ocean mean height. However for topographic surfaces, variations in the elevation can be much higher, and using a conventional altimeter causes serious problems, such as interpretation error and misregistration of a measured range, which cannot be normally corrected.
To avoid these problems, a considerably narrower beam antenna has to be used to localise the surface under observation. This requires very large antenna structures, which would be both complex and costly. This thesis investigates the application of aperture synthesis techniques to narrow-beam altimetry as an alternative to physically large antennas, to achieve high along-track resolution. It considers the analysis of the involved factors and design parameters, errors, data handling and signal processing requirements and methods for fixing the antenna beam accurately with the ultimate goal of providing a dynamic global altimetric database.
In the second half of the thesis, an experimental aircraft-borne altimeter is examined. Details of the design, construction and evaluation of a prototype system are described. This radar includes several novel features, such as aperture synthesis with full-deramp range processing, digital chirp generation, bistatic FMCW operation and off-line digital signal processing. Also a series of experiments are arranged for this radar to examine its performance to process the signature of corner reflector targets, and consideration is given to the extension of these ideas to a satellite-borne instrument
Analysis and Design of Silicon based Integrated Circuits for Radio Frequency Identification and Ranging Systems at 24GHz and 60GHz Frequency Bands
This scientific research work presents the analysis and design of radio frequency (RF) integrated circuits (ICs) designed for two cooperative RF identification (RFID) proof of concept systems. The first system concept is based on localizable and sensor-enabled superregenerative transponders (SRTs) interrogated using a 24GHz linear frequency modulated continuous wave (LFMCW) secondary radar. The second system concept focuses on low power components for a 60GHz continuous wave (CW) integrated single antenna frontend for interrogating close range passive backscatter transponders (PBTs).
In the 24GHz localizable SRT based system, a LFMCW interrogating radar sends a RF chirp signal to interrogate SRTs based on custom superregenerative amplifier (SRA) ICs. The SRTs receive the chirp and transmit it back with phase coherent amplification. The distance to the SRTs are then estimated using the round trip time of flight method. Joint data transfer from the SRT to the interrogator is enabled by a novel SRA quench frequency shift keying (SQ-FSK) based low data rate simplex communication. The SRTs are also designed to be roll invariant using bandwidth enhanced microstrip patch antennas. Theoretical analysis is done to derive expressions as a function of system parameters including the minimum SRA gain required for attaining a defined range and equations for the maximum number of symbols that can be transmitted in data transfer mode. Analysis of the dependency of quench pulse characteristics during data transfer shows that the duty cycle has to be varied while keeping the on-time constant to reduce ranging errors. Also the worsening of ranging precision at longer distances is predicted based on the non-idealities resulting from LFMCWchirp quantization due to SRT characteristics and is corroborated by system level measurements. In order to prove the system concept and study the semiconductor technology dependent factors, variants of 24GHz SRA ICs are designed in a 130nm silicon germanium (SiGe) bipolar complementary metal oxide technology (BiCMOS) and a partially depleted silicon on insulator (SOI) technology. Among the SRA ICs designed, the SiGe-BiCMOS ICs feature a novel quench pulse shaping concept to simultaneously improve the output power and minimum detectable input power. A direct antenna drive SRA IC based on a novel stacked transistor cross-coupled oscillator topology employing this concept exhibit one of the best reported combinations of minimum detected input power level of â100 dBm and output power level of 5.6 dBm, post wirebonding. The SiGe stacked transistor with base feedback capacitance topology employed in this design is analyzed to derive parameters including the SRA loop gain for design optimization. Other theoretical contributions include the analysis of the novel integrated quench pulse shaping circuit and formulas derived for output voltage swing taking bondwire losses into account. Another SiGe design variant is the buffered antenna drive SRA IC having a measured minimum detected input power level better than â80 dBm, and an output power level greater than 3.2 dBm after wirebonding. The two inputs and outputs of this IC also enables the design of roll invariant SRTs. Laboratory based ranging experiments done to test the concepts and theoretical considerations show a maximum measured distance of 77m while transferring data at the rate of 0.5 symbols per second using SQ-FSK. For distances less than 10m, the characterized accuracy is better than 11 cm and the precision is better than 2.4 cm. The combination of the maximum range, precision and accuracy are one of the best reported among similar works in literature to the authorâs knowledge.
In the 60GHz close range CW interrogator based system, the RF frontend transmits a continuous wave signal through the transmit path of a quasi circulator (QC) interfaced to an antenna to interrogate a PBT. The backscatter is received using the same antenna interfaced to the QC. The received signal is then amplified and downconverted for further processing. To prove this concept, two optimized QC ICs and a downconversion mixer IC are designed in a 22nm fully depleted SOI technology. The first QC is the transmission lines based QC which consumes a power of 5.4mW, operates at a frequency range from 56GHz to 64GHz and occupies an area of 0.49mm2. The transmit path loss is 5.7 dB, receive path gain is 2 dB and the tunable transmit path to receive path isolation is between 20 dB and 32 dB. The second QC is based on lumped elements, and operates in a relatively narrow bandwidth from 59.6GHz to 61.5GHz, has a gain of 8.5 dB and provides a tunable isolation better than 20 dB between the transmit and receive paths. This QC design also occupies a small area of 0.34mmÂČ while consuming 13.2mW power. The downconversion is realized using a novel folded switching stage down conversion mixer (FSSDM) topology optimized to achieve one of the best reported combination of maximum voltage conversion gain of 21.5 dB, a factor of 2.5 higher than reported state-of-the-art results, and low power consumption of 5.25mW. The design also employs a unique back-gate tunable intermediate frequency output stage using which a gain tuning range of 5.5 dB is attained. Theoretical analysis of the FSSDM topology is performed and equations for the RF input stage transconductance, bandwidth, voltage conversion gain and gain tuning are derived. A feasibility study for the components of the 60GHz integrated single antenna interrogator frontend is also performed using PBTs to prove the system design concept.:1 Introduction 1
1.1 Motivation and Related Work . . . . . . . . . . . . . . . . . . . . . 1
1.2 Scope and Functional Specifications . . . . . . . . . . . . . . . . . 4
1.3 Objectives and Structure . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Features and Fundamentals of RFIDs and Superregenerative Amplifiers 9
2.1 RFID Transponder Technology . . . . . . . . . . . . . . . . . . . . 9
2.1.1 Chipless RFID Transponders . . . . . . . . . . . . . . . . . 10
2.1.2 Semiconductor based RFID Transponders . . . . . . . . . . 11
2.1.2.1 Passive Transponders . . . . . . . . . . . . . . . . 11
2.1.2.2 Active Transponders . . . . . . . . . . . . . . . . . 13
2.2 RFID Interrogator Architectures . . . . . . . . . . . . . . . . . . . 18
2.2.1 Interferometer based Interrogator . . . . . . . . . . . . . . . 19
2.2.2 Ultra-wideband Interrogator . . . . . . . . . . . . . . . . . . 20
2.2.3 Continuous Wave Interrogators . . . . . . . . . . . . . . . . 21
2.3 Coupling Dependent Range and Operating Frequencies . . . . . . . 25
2.4 RFID Ranging Techniques . . . . . . . . . . . . . . . . . . . . . . . 28
2.4.0.1 Received Signal Strength based Ranging . . . . . 28
2.4.0.2 Phase based Ranging . . . . . . . . . . . . . . . . 30
2.4.0.3 Time based Ranging . . . . . . . . . . . . . . . . . 30
2.5 Architecture Selection for Proof of Concept Systems . . . . . . . . 32
2.6 Superregenerative Amplifier (SRA) . . . . . . . . . . . . . . . . . . 35
2.6.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.6.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . 42
2.6.3 Frequency Domain Characteristics . . . . . . . . . . . . . . 45
2.7 Semiconductor Technologies for RFIC Design . . . . . . . . . . . . 48
2.7.1 Silicon Germanium BiCMOS . . . . . . . . . . . . . . . . . 48
2.7.2 Silicon-on-Insulator . . . . . . . . . . . . . . . . . . . . . . . 48
3 24GHz Superregenerative Transponder based Identification and Rang-
ing System 51
3.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1.1 SRT Identification and Ranging . . . . . . . . . . . . . . . . 51
3.1.2 Power Link Analysis . . . . . . . . . . . . . . . . . . . . . . 55
3.1.3 Non-idealities . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.1.4 SRA Quench Frequency Shift Keying for data transfer . . . 61
3.1.5 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 63
3.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.2.1 Low Power Direct Antenna Drive CMOS SRA IC . . . . . . 66
3.2.1.1 Circuit analysis and design . . . . . . . . . . . . . 66
3.2.1.2 Characterization . . . . . . . . . . . . . . . . . . . 69
3.2.2 Direct Antenna Drive SiGe SRA ICs . . . . . . . . . . . . . 71
3.2.2.1 Stacked Transistor Cross-coupled Quenchable Oscillator
. . . . . . . . . . . . . . . . . . . . . . . . 72
3.2.2.1.1 Resonator . . . . . . . . . . . . . . . . . . 72
3.2.2.1.2 Output Network . . . . . . . . . . . . . . 75
3.2.2.1.3 Stacked Transistor Cross-coupled Pair and
Loop Gain . . . . . . . . . . . . . . . . . 77
3.2.2.2 Quench Waveform Design . . . . . . . . . . . . . . 85
3.2.2.3 Characterization . . . . . . . . . . . . . . . . . . . 89
3.2.3 Antenna Diversity SiGe SRA IC with Integrated Quench
Pulse Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.2.3.1 Circuit Analysis and Design . . . . . . . . . . . . 91
3.2.3.1.1 Crosscoupled Pair and Sampling Current 94
3.2.3.1.2 Common Base Input Stage . . . . . . . . 95
3.2.3.1.3 Cascode Output Stage . . . . . . . . . . . 96
3.2.3.1.4 Quench Pulse Shaping Circuit . . . . . . 96
3.2.3.1.5 Power Gain . . . . . . . . . . . . . . . . . 99
3.2.3.2 Characterization . . . . . . . . . . . . . . . . . . . 102
3.2.4 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 103
3.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 106
3.3.1 Superregenerative Transponders . . . . . . . . . . . . . . . 106
3.3.1.1 Bandwidth Enhanced Microstrip Patch Antennas 108
3.3.2 FMCW Radar Interrogator . . . . . . . . . . . . . . . . . . 114
3.3.3 Chirp Z-transform Based Data Analysis . . . . . . . . . . . 116
4 60GHz Single Antenna RFID Interrogator based Identification System 121
4.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
4.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.2.1 Quasi-circulator ICs . . . . . . . . . . . . . . . . . . . . . . 125
4.2.1.1 Transmission Lines based Quasi-Circulator IC . . 126
4.2.1.2 Lumped Elements WPD based Quasi-Circulator . 130
4.2.1.3 Characterization . . . . . . . . . . . . . . . . . . . 134
4.2.1.4 Knowledge Gained . . . . . . . . . . . . . . . . . . 135
4.2.2 Folded Switching Stage Downconversion Mixer IC . . . . . 138
4.2.2.1 FSSDM Circuit Design . . . . . . . . . . . . . . . 138
4.2.2.2 Cascode Transconductance Stage . . . . . . . . . . 138
4.2.2.3 Folded Switching Stage with LC DC Feed . . . . . 142
4.2.2.4 LO Balun . . . . . . . . . . . . . . . . . . . . . . . 145
4.2.2.5 Backgate Tunable IF Stage and Offset Correction 146
4.2.2.6 Voltage Conversion Gain . . . . . . . . . . . . . . 147
4.2.2.7 Characterization . . . . . . . . . . . . . . . . . . . 150
4.2.2.8 Knowledge Gained . . . . . . . . . . . . . . . . . . 151
4.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 154
5 Experimental Tests 157
5.1 24GHz System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
5.1.1 Ranging Experiments . . . . . . . . . . . . . . . . . . . . . 157
5.1.2 Roll Invariance Experiments . . . . . . . . . . . . . . . . . . 158
5.1.3 Joint Ranging and Data Transfer Experiments . . . . . . . 158
5.2 60GHz System Detection Experiments . . . . . . . . . . . . . . . . 165
6 Summary and Future Work 167
Appendices 171
A Derivation of Parameters for CB Amplifier with Base Feedback Capac-
itance 173
B Definitions 177
C 24GHz Experiment Setups 179
D 60 GHz Experiment Setups 183
References 185
List of Original Publications 203
List of Abbreviations 207
List of Symbols 213
List of Figures 215
List of Tables 223
Curriculum Vitae 22
Analysis and Design of Silicon based Integrated Circuits for Radio Frequency Identification and Ranging Systems at 24GHz and 60GHz Frequency Bands
This scientific research work presents the analysis and design of radio frequency (RF) integrated circuits (ICs) designed for two cooperative RF identification (RFID) proof of concept systems. The first system concept is based on localizable and sensor-enabled superregenerative transponders (SRTs) interrogated using a 24GHz linear frequency modulated continuous wave (LFMCW) secondary radar. The second system concept focuses on low power components for a 60GHz continuous wave (CW) integrated single antenna frontend for interrogating close range passive backscatter transponders (PBTs).
In the 24GHz localizable SRT based system, a LFMCW interrogating radar sends a RF chirp signal to interrogate SRTs based on custom superregenerative amplifier (SRA) ICs. The SRTs receive the chirp and transmit it back with phase coherent amplification. The distance to the SRTs are then estimated using the round trip time of flight method. Joint data transfer from the SRT to the interrogator is enabled by a novel SRA quench frequency shift keying (SQ-FSK) based low data rate simplex communication. The SRTs are also designed to be roll invariant using bandwidth enhanced microstrip patch antennas. Theoretical analysis is done to derive expressions as a function of system parameters including the minimum SRA gain required for attaining a defined range and equations for the maximum number of symbols that can be transmitted in data transfer mode. Analysis of the dependency of quench pulse characteristics during data transfer shows that the duty cycle has to be varied while keeping the on-time constant to reduce ranging errors. Also the worsening of ranging precision at longer distances is predicted based on the non-idealities resulting from LFMCWchirp quantization due to SRT characteristics and is corroborated by system level measurements. In order to prove the system concept and study the semiconductor technology dependent factors, variants of 24GHz SRA ICs are designed in a 130nm silicon germanium (SiGe) bipolar complementary metal oxide technology (BiCMOS) and a partially depleted silicon on insulator (SOI) technology. Among the SRA ICs designed, the SiGe-BiCMOS ICs feature a novel quench pulse shaping concept to simultaneously improve the output power and minimum detectable input power. A direct antenna drive SRA IC based on a novel stacked transistor cross-coupled oscillator topology employing this concept exhibit one of the best reported combinations of minimum detected input power level of â100 dBm and output power level of 5.6 dBm, post wirebonding. The SiGe stacked transistor with base feedback capacitance topology employed in this design is analyzed to derive parameters including the SRA loop gain for design optimization. Other theoretical contributions include the analysis of the novel integrated quench pulse shaping circuit and formulas derived for output voltage swing taking bondwire losses into account. Another SiGe design variant is the buffered antenna drive SRA IC having a measured minimum detected input power level better than â80 dBm, and an output power level greater than 3.2 dBm after wirebonding. The two inputs and outputs of this IC also enables the design of roll invariant SRTs. Laboratory based ranging experiments done to test the concepts and theoretical considerations show a maximum measured distance of 77m while transferring data at the rate of 0.5 symbols per second using SQ-FSK. For distances less than 10m, the characterized accuracy is better than 11 cm and the precision is better than 2.4 cm. The combination of the maximum range, precision and accuracy are one of the best reported among similar works in literature to the authorâs knowledge.
In the 60GHz close range CW interrogator based system, the RF frontend transmits a continuous wave signal through the transmit path of a quasi circulator (QC) interfaced to an antenna to interrogate a PBT. The backscatter is received using the same antenna interfaced to the QC. The received signal is then amplified and downconverted for further processing. To prove this concept, two optimized QC ICs and a downconversion mixer IC are designed in a 22nm fully depleted SOI technology. The first QC is the transmission lines based QC which consumes a power of 5.4mW, operates at a frequency range from 56GHz to 64GHz and occupies an area of 0.49mm2. The transmit path loss is 5.7 dB, receive path gain is 2 dB and the tunable transmit path to receive path isolation is between 20 dB and 32 dB. The second QC is based on lumped elements, and operates in a relatively narrow bandwidth from 59.6GHz to 61.5GHz, has a gain of 8.5 dB and provides a tunable isolation better than 20 dB between the transmit and receive paths. This QC design also occupies a small area of 0.34mmÂČ while consuming 13.2mW power. The downconversion is realized using a novel folded switching stage down conversion mixer (FSSDM) topology optimized to achieve one of the best reported combination of maximum voltage conversion gain of 21.5 dB, a factor of 2.5 higher than reported state-of-the-art results, and low power consumption of 5.25mW. The design also employs a unique back-gate tunable intermediate frequency output stage using which a gain tuning range of 5.5 dB is attained. Theoretical analysis of the FSSDM topology is performed and equations for the RF input stage transconductance, bandwidth, voltage conversion gain and gain tuning are derived. A feasibility study for the components of the 60GHz integrated single antenna interrogator frontend is also performed using PBTs to prove the system design concept.:1 Introduction 1
1.1 Motivation and Related Work . . . . . . . . . . . . . . . . . . . . . 1
1.2 Scope and Functional Specifications . . . . . . . . . . . . . . . . . 4
1.3 Objectives and Structure . . . . . . . . . . . . . . . . . . . . . . . . 5
2 Features and Fundamentals of RFIDs and Superregenerative Amplifiers 9
2.1 RFID Transponder Technology . . . . . . . . . . . . . . . . . . . . 9
2.1.1 Chipless RFID Transponders . . . . . . . . . . . . . . . . . 10
2.1.2 Semiconductor based RFID Transponders . . . . . . . . . . 11
2.1.2.1 Passive Transponders . . . . . . . . . . . . . . . . 11
2.1.2.2 Active Transponders . . . . . . . . . . . . . . . . . 13
2.2 RFID Interrogator Architectures . . . . . . . . . . . . . . . . . . . 18
2.2.1 Interferometer based Interrogator . . . . . . . . . . . . . . . 19
2.2.2 Ultra-wideband Interrogator . . . . . . . . . . . . . . . . . . 20
2.2.3 Continuous Wave Interrogators . . . . . . . . . . . . . . . . 21
2.3 Coupling Dependent Range and Operating Frequencies . . . . . . . 25
2.4 RFID Ranging Techniques . . . . . . . . . . . . . . . . . . . . . . . 28
2.4.0.1 Received Signal Strength based Ranging . . . . . 28
2.4.0.2 Phase based Ranging . . . . . . . . . . . . . . . . 30
2.4.0.3 Time based Ranging . . . . . . . . . . . . . . . . . 30
2.5 Architecture Selection for Proof of Concept Systems . . . . . . . . 32
2.6 Superregenerative Amplifier (SRA) . . . . . . . . . . . . . . . . . . 35
2.6.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . 35
2.6.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . 42
2.6.3 Frequency Domain Characteristics . . . . . . . . . . . . . . 45
2.7 Semiconductor Technologies for RFIC Design . . . . . . . . . . . . 48
2.7.1 Silicon Germanium BiCMOS . . . . . . . . . . . . . . . . . 48
2.7.2 Silicon-on-Insulator . . . . . . . . . . . . . . . . . . . . . . . 48
3 24GHz Superregenerative Transponder based Identification and Rang-
ing System 51
3.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.1.1 SRT Identification and Ranging . . . . . . . . . . . . . . . . 51
3.1.2 Power Link Analysis . . . . . . . . . . . . . . . . . . . . . . 55
3.1.3 Non-idealities . . . . . . . . . . . . . . . . . . . . . . . . . . 59
3.1.4 SRA Quench Frequency Shift Keying for data transfer . . . 61
3.1.5 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 63
3.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.2.1 Low Power Direct Antenna Drive CMOS SRA IC . . . . . . 66
3.2.1.1 Circuit analysis and design . . . . . . . . . . . . . 66
3.2.1.2 Characterization . . . . . . . . . . . . . . . . . . . 69
3.2.2 Direct Antenna Drive SiGe SRA ICs . . . . . . . . . . . . . 71
3.2.2.1 Stacked Transistor Cross-coupled Quenchable Oscillator
. . . . . . . . . . . . . . . . . . . . . . . . 72
3.2.2.1.1 Resonator . . . . . . . . . . . . . . . . . . 72
3.2.2.1.2 Output Network . . . . . . . . . . . . . . 75
3.2.2.1.3 Stacked Transistor Cross-coupled Pair and
Loop Gain . . . . . . . . . . . . . . . . . 77
3.2.2.2 Quench Waveform Design . . . . . . . . . . . . . . 85
3.2.2.3 Characterization . . . . . . . . . . . . . . . . . . . 89
3.2.3 Antenna Diversity SiGe SRA IC with Integrated Quench
Pulse Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . 91
3.2.3.1 Circuit Analysis and Design . . . . . . . . . . . . 91
3.2.3.1.1 Crosscoupled Pair and Sampling Current 94
3.2.3.1.2 Common Base Input Stage . . . . . . . . 95
3.2.3.1.3 Cascode Output Stage . . . . . . . . . . . 96
3.2.3.1.4 Quench Pulse Shaping Circuit . . . . . . 96
3.2.3.1.5 Power Gain . . . . . . . . . . . . . . . . . 99
3.2.3.2 Characterization . . . . . . . . . . . . . . . . . . . 102
3.2.4 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 103
3.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 106
3.3.1 Superregenerative Transponders . . . . . . . . . . . . . . . 106
3.3.1.1 Bandwidth Enhanced Microstrip Patch Antennas 108
3.3.2 FMCW Radar Interrogator . . . . . . . . . . . . . . . . . . 114
3.3.3 Chirp Z-transform Based Data Analysis . . . . . . . . . . . 116
4 60GHz Single Antenna RFID Interrogator based Identification System 121
4.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
4.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
4.2.1 Quasi-circulator ICs . . . . . . . . . . . . . . . . . . . . . . 125
4.2.1.1 Transmission Lines based Quasi-Circulator IC . . 126
4.2.1.2 Lumped Elements WPD based Quasi-Circulator . 130
4.2.1.3 Characterization . . . . . . . . . . . . . . . . . . . 134
4.2.1.4 Knowledge Gained . . . . . . . . . . . . . . . . . . 135
4.2.2 Folded Switching Stage Downconversion Mixer IC . . . . . 138
4.2.2.1 FSSDM Circuit Design . . . . . . . . . . . . . . . 138
4.2.2.2 Cascode Transconductance Stage . . . . . . . . . . 138
4.2.2.3 Folded Switching Stage with LC DC Feed . . . . . 142
4.2.2.4 LO Balun . . . . . . . . . . . . . . . . . . . . . . . 145
4.2.2.5 Backgate Tunable IF Stage and Offset Correction 146
4.2.2.6 Voltage Conversion Gain . . . . . . . . . . . . . . 147
4.2.2.7 Characterization . . . . . . . . . . . . . . . . . . . 150
4.2.2.8 Knowledge Gained . . . . . . . . . . . . . . . . . . 151
4.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 154
5 Experimental Tests 157
5.1 24GHz System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
5.1.1 Ranging Experiments . . . . . . . . . . . . . . . . . . . . . 157
5.1.2 Roll Invariance Experiments . . . . . . . . . . . . . . . . . . 158
5.1.3 Joint Ranging and Data Transfer Experiments . . . . . . . 158
5.2 60GHz System Detection Experiments . . . . . . . . . . . . . . . . 165
6 Summary and Future Work 167
Appendices 171
A Derivation of Parameters for CB Amplifier with Base Feedback Capac-
itance 173
B Definitions 177
C 24GHz Experiment Setups 179
D 60 GHz Experiment Setups 183
References 185
List of Original Publications 203
List of Abbreviations 207
List of Symbols 213
List of Figures 215
List of Tables 223
Curriculum Vitae 22