Millimeter-wave Communication and Radar Sensing — Opportunities, Challenges, and Solutions

With the development of communication and radar sensing technology, people are able to seek for a more convenient life and better experiences. The fifth generation (5G) mobile network provides high speed communication and internet services with a data rate up to several gigabit per second (Gbps). In addition, 5G offers great opportunities of emerging applications, for example, manufacture automation with the help of precise wireless sensing. For future communication and sensing systems, increasing capacity and accuracy is desired, which can be realized at millimeter-wave spectrum from 30 GHz to 300 GHz with several tens of GHz available bandwidth. Wavelength reduces at higher frequency, this implies more compact transceivers and antennas, and high sensing accuracy and imaging resolution. Challenges arise with these application opportunities when it comes to realizing prototype or demonstrators in practice. This thesis proposes some of the solutions addressing such challenges in a laboratory environment.High data rate millimeter-wave transmission experiments have been demonstrated with the help of advanced instrumentations. These demonstrations show the potential of transceiver chipsets. On the other hand, the real-time communication demonstrations are limited to either low modulation order signals or low symbol rate transmissions. The reason for that is the lack of commercially available high-speed analog-to-digital converters (ADCs); therefore, conventional digital synchronization methods are difficult to implement in real-time systems at very high data rates. In this thesis, two synchronous baseband receivers are proposed with carrier recovery subsystems which only require low-speed ADCs [A][B].Besides synchronization, high-frequency signal generation is also a challenge in millimeter-wave communications. The frequency divider is a critical component of a millimeter-wave frequency synthesizer. Having both wide locking range and high working frequencies is a challenge. In this thesis, a tunable delay gated ring oscillator topology is proposed for dual-mode operation and bandwidth extension [C]. Millimeter-wave radar offers advantages for high accuracy sensing. Traditional millimeter-wave radar with frequency-modulated continuous-wave (FMCW), or continuous-wave (CW), all have their disadvantages. Typically, the FMCW radar cannot share the spectrum with other FMCW radars.\ua0 With limited bandwidth, the number of FMCW radars that could coexist in the same area is limited. CW radars have a limited ambiguous distance of a wavelength. In this thesis, a phase-modulated radar with micrometer accuracy is presented [D]. It is applicable in a multi-radar scenario without occupying more bandwidth, and its ambiguous distance is also much larger than the CW radar. Orthogonal frequency-division multiplexing (OFDM) radar has similar properties. However, its traditional fast calculation method, fast Fourier transform (FFT), limits its measurement accuracy. In this thesis, an accuracy enhancement technique is introduced to increase the measurement accuracy up to the micrometer level [E]

Design of a Dual Band Local Positioning System

This work presents a robust dual band local positioning system (LPS) working in the 2.4GHz and 5.8GHz industrial science medical (ISM) bands. Position measurement is based on the frequency-modulated continuous wave (FMCW) radar approach, which uses radio frequency (RF) chirp signals for propagation time and therefore distance measurements. Contrary to state of the art LPS, the presented system uses data from both bands to improve accuracy, precision and robustness. A complete system prototype is designed consisting of base stations and tags encapsulating most of the RF and analogue signal processing in custom integrated circuits. This design approach allows to reduce size and power consumption compared to a hybrid system using off-the-shelf components. Key components are implemented using concepts, which support operation in multiple frequency bands, namely, the receiver consisting of a low noise amplifier (LNA), mixer, frequency synthesizer with a wide band voltage-controlled oscillator (VCO) having broadband chirp generation capabilities and a dual band power amplifier. System imperfections occurring in FMCW radar systems are modelled. Effects neglected in literature such as compression, intermodulation, the influence of automatic gain control, blockers and spurious emissions are modeled. The results are used to derive a specification set for the circuit design. Position estimation from measured distances is done using an enhanced version of the grid search algorithm, which makes use of data from multiple frequency bands. The algorithm is designed to be easily and efficiently implemented in embedded systems. Measurements show a coverage range of the system of at least 245m. Ranging accuracy in an outdoor scenario can be as low as 8.2cm. Comparative dual band position measurements prove an effective outlier filtering in indoor and outdoor scenarios compared to single band results, yielding in a large gain of accuracy. Positioning accuracy in an indoor scenario with an area of 276m² can be improved from 1.27m at 2.4GHz and 1.86m at 5.8GHz to only 0.38m in the dual band case, corresponding to an improvement by at least a factor of 3.3. In a large outdoor scenario of 4.8 km², accuracy improves from 1.88m at 2.4GHz and 5.93m at 5.8GHz to 0.68m with dual band processing, which is a factor of at least 2.8.Die vorliegende Arbeit befasst sich mit dem Entwurf eines robusten lokalen Positionierungssystems (LPS), welches in den lizenzfreien Frequenzbereichen für industrielle, wissenschaftliche und medizinische Zwecke (industrial, scientific, medical, ISM) bei 2,4GHz und 5,8GHz arbeitet. Die Positionsbestimmung beruht auf dem Prinzip des frequenzmodulierten Dauerstrichradars (frequency modulated continuous wave, FMCW-Radar), welches hochfrequente Rampensignale für Laufzeitmessungen und damit Abstandsmessungen benutzt. Im Gegensatz zu aktuellen Arbeiten auf diesem Gebiet benutzt das vorgestellte System Daten aus beiden Frequenzbändern zur Erhöhung der Genauigkeit und Präzision sowie Verbesserung der Robustheit. Ein Prototyp des kompletten Systems bestehend aus Basisstationen und mobilen Stationen wurde entworfen. Fast die gesamte analoge hochfrequente Signalverarbeitungskette wurde als anwendungsspezifische integrierte Schaltung realisiert. Verglichen mit Systemen aus Standardkomponenten erlaubt dieser Ansatz die Miniaturisierung der Systemkomponenten und die Einsparung von Leistung. Schlüsselkomponenten wurden mit Konzepten für mehrbandige oder breitbandige Schaltungen entworfen. Dabei wurden Sender und Empfänger bestehend aus rauscharmem Verstärker, Mischer und Frequenzsynthesizer mit breitbandiger Frequenzrampenfunktion implementiert. Außerdem wurde ein Leistungsverstärker für die gleichzeitige Nutzung der beiden definierten Frequenzbänder entworfen. Um Spezifikationen für den Schaltungsentwurf zu erhalten, wurden in der Fachliteratur vernachlässigte Nichtidealitäten von FMCW-Radarsystemen modelliert. Dazu gehören Signalverzerrungen durch Kompression oder Intermodulation, der Einfluss der automatischen Verstärkungseinstellung sowie schmalbandige Störer und Nebenschwingungen. Die Ergebnisse der Modellierung wurden benutzt, um eine Spezifikation für den Schaltungsentwurf zu erhalten. Die Schätzung der Position aus gemessenen Abständen wurde über eine erweiterte Version des Gittersuchalgorithmus erreicht. Dieser nutzt die Abstandsmessdaten aus beiden Frequenzbändern. Der Algorithmus ist so entworfen, dass er effizient in einem eingebetteten System implementiert werden kann. Messungen zeigen eine maximale Reichweite des Systems von mindestens 245m. Die Genauigkeit von Abstandsmessungen im Freiland beträgt 8,2cm. Positionsmessungen wurden unter Verwendung beider Einzelbänder durchgeführt und mit den Ergebnissen des Zweiband-Gittersuchalgorithmus verglichen. Damit konnte eine starke Verbesserung der Positionsgenauigkeit erreicht werden. Die Genauigkeit in einem Innenraum mit einer Grundfläche von 276m² kann verbessert werden von 1,27m bei 2,4GHz und 1,86m bei 5,8GHz zu nur 0,38m im Zweibandverfahren. Das entspricht einer Verbesserung um einen Faktor von mindestens 3,3. In einem größeren Außenszenario mit einer Fläche von 4,8 km² verbessert sich die Genauigkeit um einen Faktor von mindestens 2,8 von 1,88m bei 2,4GHz und 5,93m bei 5,8GHz auf 0,68m bei Nutzung von Daten aus beiden Frequenzbändern

Phase-sensitive FMCW radar system for high-precision Antarctic ice shelf profile monitoring

Ice shelves fringe much of the Antarctic continent, and, despite being up to 2 km thick, are vulnerable to climate change. Owing to their role in helping to control the ice sheet contribution to sea level change there is great interest in measuring the rate at which they are melting into the ocean. This study describes the development and deployment of an ice-penetrating phase-sensitive FMCW radar, sufficiently robust and with sufficiently low-power consumption to be run through the Antarctic winter as a standalone instrument, yet with the stability and mm-precision needed to detect the very slow changes in ice shelf thickness in this exceptionally demanding environment. A number of elegant processing techniques are described to achieve reliable, high-precision performance and results presented on field data obtained from the Larsen-C ice shelf, Antarctica

Statistical Study of Hardware Impairments Effect on mmWave 77 GHz FMCW Automotive Radar

In this paper, we analyze the effects of hardwareimpairments on 77GHz FMCW automotive radar performance.Joint in-phase/quadrature imbalance (IQI) and phase noise effects on frequency-modulated continuous-wave (FMCW) radar transceiverfront-end is modeled through statistical analysis of distortionand noise. We derive the signal to distortion plus noise ratio,constant false alarm rate, and range-Doppler sensitivity analysisfor both the joint and the individual effects of impairmentsand validate the formulations with simulations. The representedmodeling and analysis can be used in millimeter wave (mmWave) FMCW automotiveradar signal processing algorithms for optimum transceiverdesign

Millimeter-Wave Super-Regenerative Receivers for Wireless Communication and Radar

Today’s world is becoming increasingly automated and interconnected with billions of smart devices coming online, leading to a steep rise in energy consumption from small microelectronics. This coincides with an urgent push to transform global energy production to green energies, causing disruptions and energy shortages, and making the case for efficient energy use ever more pressing. Two major areas where high growth is expected are the fields of wireless communication and radar sensors. Millimeter-wave frequency bands are planned for fifth-generation (5G) and sixth-generation (6G) cellular communication standards, as well as automotive frequency-modulated continuous wave (FMCW) radar systems for driving assistance and automation. Fast silicon-based technologies enable these advances by operating at high maximum frequencies, such as the silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) technologies. However, even the fastest transistors suffer from low and energy expensive gains at millimeter-wave frequencies. Rather than incremental improvements in circuit efficiency using conventional approaches, a disruptive revolution for green microelectronics could be enabled by exploring the low-power benefits of the super-regenerative receiver for some applications. The super-regenerative receiver uses a regenerative oscillator circuit to increase the gain by positive feedback, through coupling energy from the output back into the input. Careful bias and control of the circuit enables a very large gain from a small number of transistors and a very low energy dissipation. Thus, the super-regenerative oscillator could be used to replace amplifier circuits in high data rate wireless communication systems, or as active reflectors to increase the range of FMCW radar systems, greatly reducing the power consumption. The work in this thesis presents fundamental scientific research into the topic of energy-efficient millimeter-wave super-regenerative receivers for use in civilian wireless communication and radar applications. This research work covers the theory, analysis, and simulations, all the way up to the proof of concept, hardware realization, and experimental characterization. Analysis and modeling of regenerative oscillator circuits is presented and used to improve the understanding of the circuit operation, as well as design goals according to the specific application needs. Integrated circuits are investigated and characterized as a proof of concept for a high data rate wireless communication system operating between 140–220 GHz, and an automotive radar system operating at 60 GHz. Amplitude and phase regeneration capabilities for complex modulation are investigated, and principles for spectrum characterization are derived. The circuits are designed and fabricated in a 130 nm SiGe HBT technology, combining bipolar and complementary metal-oxide semiconductor (BiCMOS) transistors. To prove the feasibility of the research concepts, the work achieves a wireless communication link at 16 Gbit/s over 20 cm distance with quadrature amplitude modulation (QAM), which is a world record for the highest data rate ever reported in super-regenerative circuits. This was powered by a super-regenerative oscillator circuit operating at 180 GHz and providing 58 dB of gain. Energy efficiency is also considerably high, drawing 8.8 mW of dc power consumption, which corresponds to a highly efficient 0.6 pJ/bit. Packaging and module integration innovations were implemented for the system experiments, and additional broadband circuits were investigated to generate custom quench waveforms to further enhance the data rate. For radar active reflectors, a regenerative gain of 80 dB is achieved at 60 GHz from a single circuit, which is the best in its frequency range, despite a low dc power consumption of 25 mW

A LINEARIZATION METHOD FOR A UWB VCO-BASED CHIRP GENERATOR USING DUAL COMPENSATION

Ultra-Wideband (UWB) chirp generators are used on Frequency Modulated Continuous Wave (FMCW) radar systems for high-resolution and high-accuracy range measurements. At the Center for Remote Sensing of Ice Sheets (CReSIS), we have developed two UWB radar sensors for high resolution measurements of surface elevation and snow cover over Greenland and Antarctica. These radar systems are routinely operated from both surface and airborne platforms. Low cost implementations of UWB chirp generators are possible using an UWB Voltage Controlled Oscillator (VCO). VCOs possess several advantages over other competing technologies, but their frequency-voltage tuning characteristics are inherently non-linear. This nonlinear relationship between the tuning voltage and the output frequency should be corrected with a linearization system to implement a linear frequency modulated (LFM) waveform, also known as a chirp. If the waveform is not properly linearized, undesired additional frequency modulation is found in the waveform. This additional frequency modulation results in undesired sidebands at the frequency spectrum of the Intermediate Frequency (IF) stage of the FMCW radar. Since the spectrum of the filtered IF stage represents the measured range, the uncorrected nonlinear behavior of the VCO will cause a degradation of the range sensing performance of a FMCW radar. This issue is intensified as the chirp rate and nominal range of the target increase. A linearization method has been developed to linearize the output of a VCO-based chirp generator with 6 GHz of bandwidth. The linearization system is composed of a Phase Lock Loop (PLL) and an external compensation added to the loop. The nonlinear behavior of the VCO was treated as added disturbances to the loop, and a wide loop bandwidth PLL was designed for wideband compensation of these disturbances. Moreover, the PLL requires a loop filter able to attenuate the reference spurs. The PLL has been designed with a loop bandwidth as wide as possible while maintaining the reference spur level below 35 dBc. Several design considerations were made for the large loop bandwidth design. Furthermore, the large variations in the tuning sensitivity of the oscillator forced a design with a large phase margin at the average tuning sensitivity. This design constraint degraded the tracking performance of the PLL. A second compensation signal, externally generated, was added to the compensation signal of the PLL. By adding a compensation signal, which was not affected by the frequency response effects of the loop compensation, the loop tracking error is reduced. This technique enabled us to produce an output chirp signal that is a much closer replica of the scaled version of the reference signal. Furthermore, a type 1 PLL was chosen for improved transient response, compared to that of the type 2 PLL. This type of PLL requires an external compensation to obtain a finite steady state error when applying a frequency ramp to the input. The external compensation signal required to solve this issue was included in the second compensation signal mentioned above. Measurements for the PLL performance and the chirp generator performance were performed in the laboratory using a radar demonstrator. The experimental results show that the designed loop bandwidth was successfully achieved without significantly increasing the spurious signal level. The chirp generator measurements show a direct relationship between the bandwidth of the external compensation and the range resolution performance

Investigation of Non-coherent Discrete Target Range Estimation Techniques for High-precision Location

Ranging is an essential and crucial task for radar systems. How to solve the range-detection problem effectively and precisely is massively important. Meanwhile, unambiguity and high resolution are the points of interest as well. Coherent and non-coherent techniques can be applied to achieve range estimation, and both of them have advantages and disadvantages. Coherent estimates offer higher precision but are more vulnerable to noise and clutter and phase wrap errors, particularly in a complex or harsh environment, while the non-coherent approaches are simpler but provide lower precision. With the purpose of mitigating inaccuracy and perturbation in range estimation, miscellaneous techniques are employed to achieve optimally precise detection. Numerous elegant processing solutions stemming from non-coherent estimate are now introduced into the coherent realm, and vice versa. This thesis describes two non-coherent ranging estimate techniques with novel algorithms to mitigate the instinct deficit of non-coherent ranging approaches. One technique is based on peak detection and realised by Kth-order Polynomial Interpolation, while another is based on Z-transform and realised by Most-likelihood Chirp Z-transform. A two-stage approach for the fine ranging estimate is applied to the Discrete Fourier transform domain of both algorithms. An N-point Discrete Fourier transform is implemented to attain a coarse estimation; an accurate process around the point of interest determined in the first stage is conducted. For KPI technique, it interpolates around the peak of Discrete Fourier transform profiles of the chirp signal to achieve accurate interpolation and optimum precision. For Most-likelihood Chirp Z-transform technique, the Chirp Z-transform accurately implements the periodogram where only a narrow band spectrum is processed. Furthermore, the concept of most-likelihood estimator is introduced to combine with Chirp Z-transform to acquire better ranging performance. Cramer-Rao lower bound is presented to evaluate the performance of these two techniques from the perspective of statistical signal processing. Mathematical derivation, simulation modelling, theoretical analysis and experimental validation are conducted to assess technique performance. Further research will be pushed forward to algorithm optimisation and system development of a location system using non-coherent techniques and make a comparison to a coherent approach

Time-Offset Fractional-N PLLs for Heterodyne FMCW SAR

This text contains an investigation into the use of time-offset fractional-N phase locked loops (PLLs) for heterodyne frequency-modulated continuous-wave (FMCW) synthetic aperture radar (SAR) and the impact of spurii on such a system. Heterodyne receiver architectures avoid phenomena which limit the sensitivity of their homodyne counterparts, and enable certain inter-antenna feed-through suppression techniques. Despite these advantages, homodyne receivers are more prevalent owing to advantages in size, weight and cost. Designed to address this dilemma, the miloSAR is believed to be the only heterodyne FMCW SAR to employ a pair of time-offset fractional-N PLLs for waveform synthesis to enable low-cost heterodyning and simplify filter-based feed-through suppression. This system architecture is revealed to be susceptible to swept-offset spurii termed spur chirps which hinder the sensor's performance. While integer boundary spurs and phase detector harmonics infamously plague fractional-N PLLs, their resultant spur-chirps have not seen analysis in the context of FMCW SAR. Simulations and measurements reveal that these spurii significantly degrade SAR image quality in terms of peak sidelobe ratio, structural similarity index measure and root mean square error. To combat this, several suppression techniques were assessed, namely: time domain zeroing, PLL loop bandwidth reduction, and a novel method termed range-Doppler spur masking. A subset of these suppression techniques were applied to measured SAR data sets, including car-borne data measured in Iowa, USA and airborne data captured in Oudtshoorn, South Africa. These results show that the impact of spur chirps can be effectively quelled, meaning that time-offset fractional-N PLLs offer an attractive, low-cost approach to the implementation of heterodyne FMCW SAR

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 −100 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 −80 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 author’s 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 0.34mm² 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