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Frequency synthesizers are essential components for modern wireless and wireline communication systems as they provide the local oscillator signal required to transmit and receive data at very high rates. They are also vital for computing devices and microcontrollers as they generate the clocks required to run all the digital circuitry responsible for the high speed computations. Data rates and clocking speeds are continuously increasing to accommodate for the ever growing demand on data and computational power. This places stringent requirements on the performance metrics of frequency synthesizers. They are required to run at higher speeds, cover a wide range of frequencies, provide a low jitter/phase noise output and consume minimum power and area. In this work, we present new techniques and architectures for implementing high speed frequency synthesizers which fulfill the aforementioned requirements. We propose a new architecture and design approach for the realization of wideband millimeter-wave frequency synthesizers. This architecture uses two-step multi-order harmonic generation of a low frequency phase-locked signal to generate wideband mm-wave frequencies. A prototype of the proposed system is designed and fabricated in 90nm Complementary Metal Oxide Semiconductor (CMOS) technology. Measurement results demonstrated that a very wide tuning range of 5 to 32 GHz can be achieved, which is costly to implement using conventional techniques. Moreover the power consumption per octave resembles that of state-of-the art reports. Next, we propose the N-Push cyclic coupled ring oscillator (CCRO) architecture to implement two high performance oscillators: (1) a wideband N-Push/M-Push CCRO operating from 3.16-12.8GHz implemented by two harmonic generation operations using the availability of different phases from the CCRO, and (2) a 13-25GHz millimeter-wave N-Push CCRO with a low phase noise performance of -118dBc/Hz at 10MHz. The proposed oscillators achieve low phase noise with higher FOM than state of the art work. Finally, we present some improvement techniques applied to the performance of phase locked loops (PLLs). We present an adaptive low pass filtering technique which can reduce the reference spur of integer-N charge-pump based PLLs by around 20dB while maintaining the settling time of the original PLL. Another PLL is presented, which features very low power consumption targeting the Medical Implantable Communication Standard. It operates at 402-405 MHz while consuming 600microW from a 1V supply.

<p>Since their introduction by Mercedes Benz in the late 1990s, W-band radars operating at 76-77 GHz have found their way into more and more passenger cars. These automotive radars are typically used in adaptive cruise control, pre-collision sensing, and other driver assistance systems. While these systems are usually only about the size of two stacked cigarette packs, system size, and weight remains a concern for many automotive manufacturers.</p><p>In this dissertation, I discuss how artificially structured metamaterials can be used to improve lens-based automotive radar systems. Metamaterials allow the fabrication of smaller and lighter systems, while still meeting the frequency, high gain, and cost requirements of this application. In particular, I focus on the development of planar artificial dielectric lenses suitable for use in place of the injection-molded lenses now used in many automotive radar systems.</p><p>I begin by using analytic and numerical ray-tracing to compare the performance of planar metamaterial GRIN lenses to equivalent aspheric refractive lenses. I do this to determine whether metamaterials are best employed in GRIN or refractive automotive radar lenses. Through this study I find that planar GRIN lenses with the large refractive index ranges enabled by metamaterials have approximately optically equivalent performance to equivalent refractive lenses for fields of view approaching ±20°. I also find that the uniaxial nature of most planar metamaterials does not negatively impact planar GRIN lens performance.</p><p>I then turn my attention to implementing these planar GRIN lenses at W-band automotive radar frequencies. I begin by designing uniform sheets of W-band electrically-coupled LC resonator-based metamaterials. These metamaterial samples were fabricated by the Jokerst research group on glass and liquid crystal polymer (LCP) substrates and tested at Toyota Research Institute- North America (TRI-NA). When characterized at W-band frequencies, these metamaterials show material properties closely matching those predicted by full-wave simulations.</p><p>Due to the high losses associated with resonant metamaterials, I shift my focus to non-resonant metamaterials. I discuss the design, fabrication, and testing of non-resonant metamaterials for fabrication on multilayer LCP printed circuit boards (PCBs). I then use these non-resonant metamaterials in a W-band planar metamaterial GRIN lens. Radiation pattern measurements show that this lens functions as a strong collimating element.</p><p>Using similar lens design methods, I design a metamaterial GRIN lens from polytetrafluoroethylene-based (PTFE-based) non-resonant metamaterials. This GRIN lens is designed to match a target dielectric lens's radiation characteristics across a ±6° field of view. Measurements at automotive radar frequencies show that this lens has approximately the same radiation characteristics as the target lens across the desired field of view.</p><p>Finally, I describe the development of electrically reconfigurable metamaterials using thin-film silicon semiconductors. These silicon-based reconfigurable metamaterials were developed in close collaboration with several other researchers. My major contribution to the development of these reconfigurable metamaterials consisted of the initial metamaterial design. The Jokerst research group fabricated this initial design while TRI-NA characterized the fabricated metamaterial experimentally. Measurements showed approximately 8% variation in transmission under a 5 Volt DC bias. This variation in transmission closely matched the variation in transmission predicted by coupled electronic-electromagnetic simulation run by Yaroslav Urzhumov, one of other contributors to the development of the reconfigurable metamaterial.</p> / Dissertation

Recently, there have been a great interest in the millimeter-wave (mmW) and terahertz (THz) bands due to the unique features they provide for various applications. For example, the mmW is not significantly affected by the atmospheric constraints and it can penetrate through clothing and other dielectric materials. Therefore, it is suitable for a vast range of imaging applications such as vision, safety, health, environmental studies, security and non-destructive testing. Millimeter-wave imaging systems have been conventionally used for high end applications implementing sophisticated and expensive technologies. Recent advancements in the silicon integrated and low loss material passive technologies have created a great opportunity to study the feasibility of low cost mmW imaging systems. However, there are several challenges to be addressed first. Examples are modeling of active and passive devices and their low performance, highly attenuated channel and poor signal to noise ratio in the mmW. The main objective of this thesis is to investigate and develop new technologies enabling cost-effective implementation of mmW and sub-mmW imaging systems. To achieve this goal, an integrated active Rotman lens architecture is proposed as an ultimate solution to combine the unique properties of a Rotman lens with the superiority of CMOS technology for fabrication of cost effective integrated mmW systems. However, due to the limited sensitivity of on-chip detectors in the mmW, a large number of high gain, wide-band and miniaturized mmW Low Noise Amplifiers (LNA) are required to implement the proposed integrated Rotman lens architecture. A unique solution presented in this thesis is the novel Band Pass Distributed Amplifier (BPDA) topology. In this new topology, by short circuiting the line terminations in a Conventional Distributed Amplifier (CDA), standing waves are created in its artificial transmission lines. Conventionally, standing waves are strongly avoided by carefully matching these lines to 50 ?? in order to prevent instability of the amplifier. This causes that a large portion of the signal be absorbed in these resistive terminations. In this thesis, it is shown that due to presence of highly lossy parasitics of CMOS transistor at the mmW the amplifier stability is inherently achieved. Moreover, by eliminating these lossy and noise terminations in the CDA, the amplifier gain is boosted and its noise figure is reduced. In addition, a considerable decrease in the number of elements enables low power realization of many amplifiers in a small chip area. Using the lumped element model of the transistor, the transfer function of a single stage BPDAs is derived and compared to its conventional counter part. A methodology to design a single stage BPDA to achieve all the design goals is presented. Using the presented design guidelines, amplifiers for different mmW frequencies have been designed, fabricated and tested. Using only 4 transistors, a 60 GHz amplifier is fabricated on a very small chip area of 0.105 mm2 by a low-cost 130 nm CMOS technology. A peak gain of 14.7 dB and a noise figure of 6 dB are measured for this fabricated amplifier. oreover, it is shown that by further circuit optimization, high gain amplification can be realized at frequencies above the cut-off frequency of the transistor. Simulations show 32 and 28 dB gain can be obtained by implementing only 6 transistors using this CMOS technology at 60 and 77 GHz. A 4-stage 85 GHz amplifier is also designed and fabricated and a measured gain of 10 dB at 82 GHz is achieved with a 3 dB bandwidth of 11 GHz from 80 to 91 GHz. A good agreement between the simulated and measured results verifies the accuracy of the design procedure. In addition, a multi-stage wide-band BPDA has been designed to show the ability of the proposed topology for design of wide band mmW amplifiers using the CMOS technology. Simulated gain of 20.5 dB with a considerable 3 dB bandwidth of 38 GHz from 30 to 68 GHz is achieved while the noise figure is less than 6 dB in the whole bandwidth. An amplifier figure of merit is defined in terms of gain, noise figure, chip area, band width and power consumption. The results are compared to those of the state of the art to demonstrate the advantages of the proposed circuit topology and presented design techniques. Finally, a Rotman lens is designed and optimized by choosing a very small Focal Lens Ratio (FL), and a high measured efficiency of greater than 30% is achieved while the lens dimensions are less than 6 mm. The lens is designed and implemented using a low cost Alumina substrate and conventional microstrip lines to ease its integration with the active parts of the system.

Millimeter-wave has been a medium for automotive, sensor, and defense applications for a long time. But, a fully integrated silicon-based transceiver at 60 GHz or higher frequencies has become the driving force for recent research activities in integrated millimeter-wave (MMW) circuit designs. However, no integrated compact high-performance millimeter-wave system can be designed without accurate estimation and optimization of layout parasitics. In this dissertation, the estimation, modeling and optimization of parasitic effects as well as the verification of extraction methodologies for RF/MMW applications are investigated. Different circuit design- and layout-examples are considered with stress on the inclusion and optimization of wire/interconnect parasitics. A novel methodology is proposed to reduce the number of design-passes and to include layout parasitics in the design optimization procedure. An automated verification procedure for existing parasitic extraction tools is developed. Neural-network-based models are used to demonstrate the effectiveness of artificial intelligence techniques for characterizing parasitic components. The parasitic sensitivities for selected millimeter-wave circuits are demonstrated, and a parasitic benchmarking procedure is developed using MMW oscillators. Measurement results of several circuits that are implemented in state-of-the-art CMOS and SiGe-BiCMOS processes are used to demonstrate the role of parasitics and the systematic design methodology including parasitics.

Component design for a proposed 60 GHz short-range low-power high-data-rate On-Off Keying receiver in a 90 nm CMOS process is presented. The advances in RFCMOS and the commercial need for high data-rate wireless links are discussed as the enabling technology and motivation for research into the development of 60 GHz CMOS radios for wireless personal area networks. System level calculations are presented validating the feasibility of the proposed receiver topology for its target application. The design and simulation results of a 60 GHz low noise amplifier, 60 GHz direct-conversion demodulator (which has generated an invention disclosure), and a baseband amplifier are discussed in detail. Also presented is a discussion of device modeling techniques for millimeter-wave designs. Measured results are presented for the demodulator. Finally, recommendations for future work are presented.

"December, 2003" / Includes bibliographical references (p. 311-348) / Accompanying CD-ROM entitled: 'SPM_PhD_Thesis' contains MATLAB_Algorithms (algorithms for T-ray data analysis and display, as described in the Thesis); Appendix D (Example_Raw_Data_Files - examples of raw T-ray data files, used by the MATLAB algorithms in MATLAB_Algorithms); and Thesis_PDF (a copy of the Thesis printed in Adobe's Portable Document Format (PDF)). / System requirements for accompanying CD-ROM: CD-ROM drive ; Adobe Acrobat reader ; Matlab software. / xxxiv, 358 p. : ill. (col.) ; 30 cm. + 1 CD-ROM (col. ill. ; 4 3/4 in.) / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Electrical and Electronic Engineering, 2004

Thesis (Ph.D.)--University of Adelaide, School of Electrical and Electronic Engineering, 2004. / "December, 2003" Includes bibliographical references (p. 311-348).

Thesis (Ph.D.)--University of Adelaide, School of Electrical and Electronic Engineering, 2005. / Includes bibliographical references (p. 349-379) and index.

Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008. / Committee Chair: John Papapolymerou; Committee Chair: Manos Tentzeris; Committee Member: Gordon Stuber; Committee Member: John Cressler; Committee Member: John Z. Zhang; Committee Member: Joy Laskar