Design of Energy-Efficient A/D Converters with Partial Embedded Equalization for High-Speed Wireline Receiver Applications

As the data rates of wireline communication links increases, channel impairments such as skin effect, dielectric loss, fiber dispersion, reflections and cross-talk become more pronounced. This warrants more interest in analog-to-digital converter (ADC)-based serial link receivers, as they allow for more complex and flexible back-end digital signal processing (DSP) relative to binary or mixed-signal receivers. Utilizing this back-end DSP allows for complex digital equalization and more bandwidth-efficient modulation schemes, while also displaying reduced process/voltage/temperature (PVT) sensitivity. Furthermore, these architectures offer straightforward design translation and can directly leverage the area and power scaling offered by new CMOS technology nodes. However, the power consumption of the ADC front-end and subsequent digital signal processing is a major issue. Embedding partial equalization inside the front-end ADC can potentially result in lowering the complexity of back-end DSP and/or decreasing the ADC resolution requirement, which results in a more energy-effcient receiver. This dissertation presents efficient implementations for multi-GS/s time-interleaved ADCs with partial embedded equalization. First prototype details a 6b 1.6GS/s ADC with a novel embedded redundant-cycle 1-tap DFE structure in 90nm CMOS. The other two prototypes explain more complex 6b 10GS/s ADCs with efficiently embedded feed-forward equalization (FFE) and decision feedback equalization (DFE) in 65nm CMOS. Leveraging a time-interleaved successive approximation ADC architecture, new structures for embedded DFE and FFE are proposed with low power/area overhead. Measurement results over FR4 channels verify the effectiveness of proposed embedded equalization schemes. The comparison of fabricated prototypes against state-of-the-art general-purpose ADCs at similar speed/resolution range shows comparable performances, while the proposed architectures include embedded equalization as well

On time, time synchronization and noise in time measurement systems

Time plays an important role in our modern lives. Especially having accurate time, which in turn depends on having clocks being synchronized to each other. This thesis is split into three distinct parts. The first part deals with the mathematical description of noise that is required to model clocks and electronics accurately. In particular we will address the problem that the generally used tools from signal theory fail for noise signals which are neither of finite energy nor periodic in nature. For this we will introduce a new function space based on the Pp-seminorm that is an extension of the Lp-norm for functions of potentially infinite energy but limited power. Using this new semi-norm we will modify the Fourier transform to work on signals from this P p-space. And last but not least, we will introduce, based on the above, a new mathematical model of noise that captures all the properties associated with 1/f -noise. In the second part, we will look at how noise propagates in a few classes of electronics, especially how the non-linear behavior of electronics leads to an amplification of noise and how it could be miti-gated. Lastly, in the third part we will look at one approach of fault-tolerant clock synchronization. After explaining its working principle and showing an implementation in an FPGA we will focus on meta-stability, the problems it can cause and how to handle them on two different circuit levels.Zeit spielt eine wichtige Rolle in unserem Leben. Insbesondere die Verfügbarkeit einer genauen Zeit. Welches wiederum davon abhängt, dass man Uhren hat die auf einander synchronisiert laufen. Diese Arbeit ist in drei Teile aufgeteilt: Im ersten Teil betrachten wir die mathematische Beschreibung von Rauschen um elektronische Systeme und Uhren korrekt beschreiben zu können. Im Besonderen betrachten wir die Probleme die die generell benutzten Methoden der Signalverarbeitung beim Umgang mit Rauschsignalen haben, die weder energiebegrenzt noch periodisch sind. Dafür erweitern wir den Funktionenraum der Lp-Norm auf leistungslimiterte Funktionene und führen die Pp-Halbnorm ein und modifizieren die Fouriertransformation zur Verwendung auf diesen Raum. Und letztlich führen wir ein neues mathematisches Model zur Beschreibung von Rauschen ein, welches alle üblicherweise angenommenen Eigenschaften gleichzeitig erfüllt. Im zweiten Teil analysieren wir wie sich einige Klassen von elektronischen Schaltungem im Bezug auf Rauschen verhalten. Insbesondere im Bezug auf das nicht-lineare Verhalten der elektronischen Elemente, welches zu einer Verstärkung des Rauschens führt. Im dritten Teil betrachten wir eine Möglichkeit um fehlertolerante Synchronization von Uhren zu erreichen. Nach einem Überblick über den verwendeten Algorithmus und wie dieser einem FPGA implementiert werden kann, schauen wir uns den Einfluss von Metastabilität an und wie dieser eingedämmt werden kann

Ultra Compact and Low-power TDC and TAC Architectures for Highly-Parallel Implementation in Time-Resolved Image Sensors

We report on the design and characterization of three different architectures, namely two Time-to- Digital Converters (TDCs) and a Time-to-Amplitude Converter (TAC) with embedded analog-to-digital conversion, implemented in a 130-nm CMOS imaging technology. The proposed circuit solutions are conceived for implementation at pixel-level, in image sensors exploiting Single-Photon Avalanche Diodes as photodetectors. The fabricated 32x32 TDCs/TACs arrays have a pitch of 50μm in both directions while the average power consumption is between 28mW and 300mW depending on the architectural choice. The TAC achieves a time resolution of 160ps on a 20-ns time range with a differential and integral non-linearity (DNL, INL) of 0.7LSB and 1.9LSB, respectively. The two TDCs have a 10-bit resolution with a minimum time resolution between 50ps and 119ps and a worst-case accuracy of ±0.5 LSB DNL and 2.4 LSB INL. An overview of the performance is given together with the analysis of the pros and cons for each architecture

Integrated Circuit Design for Radiation Sensing and Hardening.

Beyond the 1950s, integrated circuits have been widely used in a number of electronic devices surrounding people’s lives. In addition to computing electronics, scientific and medical equipment have also been undergone a metamorphosis, especially in radiation related fields where compact and precision radiation detection systems for nuclear power plants, positron emission tomography (PET), and radiation hardened by design (RHBD) circuits for space applications fabricated in advanced manufacturing technologies are exposed to the non-negligible probability of soft errors by radiation impact events. The integrated circuit design for radiation measurement equipment not only leads to numerous advantages on size and power consumption, but also raises many challenges regarding the speed and noise to replace conventional design modalities. This thesis presents solutions to front-end receiver designs for radiation sensors as well as an error detection and correction method to microprocessor designs under the condition of soft error occurrence. For the first preamplifier design, a novel technique that enhances the bandwidth and suppresses the input current noise by using two inductors is discussed. With the dual-inductor TIA signal processing configuration, one can reduce the fabrication cost, the area overhead, and the power consumption in a fast readout package. The second front-end receiver is a novel detector capacitance compensation technique by using the Miller effect. The fabricated CSA exhibits minimal variation in the pulse shape as the detector capacitance is increased. Lastly, a modified D flip-flop is discussed that is called Razor-Lite using charge-sharing at internal nodes to provide a compact EDAC design for modern well-balanced processors and RHBD against soft errors by SEE.PhDElectrical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111548/1/iykwon_1.pd

Delay Measurements and Self Characterisation on FPGAs

This thesis examines new timing measurement methods for self delay characterisation of Field-Programmable Gate Arrays (FPGAs) components and delay measurement of complex circuits on FPGAs. Two novel measurement techniques based on analysis of a circuit's output failure rate and transition probability is proposed for accurate, precise and efficient measurement of propagation delays. The transition probability based method is especially attractive, since it requires no modifications in the circuit-under-test and requires little hardware resources, making it an ideal method for physical delay analysis of FPGA circuits. The relentless advancements in process technology has led to smaller and denser transistors in integrated circuits. While FPGA users benefit from this in terms of increased hardware resources for more complex designs, the actual productivity with FPGA in terms of timing performance (operating frequency, latency and throughput) has lagged behind the potential improvements from the improved technology due to delay variability in FPGA components and the inaccuracy of timing models used in FPGA timing analysis. The ability to measure delay of any arbitrary circuit on FPGA offers many opportunities for on-chip characterisation and physical timing analysis, allowing delay variability to be accurately tracked and variation-aware optimisations to be developed, reducing the productivity gap observed in today's FPGA designs. The measurement techniques are developed into complete self measurement and characterisation platforms in this thesis, demonstrating their practical uses in actual FPGA hardware for cross-chip delay characterisation and accurate delay measurement of both complex combinatorial and sequential circuits, further reinforcing their positions in solving the delay variability problem in FPGAs

The Effect of Ultrasonic Vibration on the Solidification of Light Alloys

This exposition presents the novel thermodynamical and microstructural modification to light alloys, such as aluminum alloys and magnesium alloys, by ultrasonic vibrations during their solidification processes. Ultrasonic vibration has proven to be effective in controlling columnar dendritic structure, reducing the size of equiaxed grains, and under some conditions, producing globular non-dendritic grains. Despite this, the solidification process under the effect of ultrasonic vibration was not clear. Not only was there no such research on how ultrasonic vibration affected its solidification thermodynamically, but also its effects on the as-cast microstructure, including the primary fcc phase, the eutectics, and the secondary phases, were not systematically studied. In addition, most studies had been empirical and phenomenological rather than quantitative. Prior to the experiments, thermodynamic simulations were carried out using the Scheil model to determine the temperature versus solid fraction curve of the alloys. The starting temperature for ultrasonic processing and the casting temperature were predetermined according to the simulation result. An experimental apparatus which supplied a powerful 1500 Watts at 20 KHz of ultrasonic power was designed and built. Thermal analysis experiments were performed. The result shows that, with ultrasonic vibration, the steady growth temperature and the minimum supercooling temperature have been elevated; while the recalescence time decreased, which indicates a much slower growth rate of primary fcc aluminum grains. The difference between dendrites nucleation/growth and thickening is not significant in the casting with ultrasonic vibration, which might suggest dendrites formation might not present in this solidification process. The mechanisms for ultrasonic influence on solidification have been discussed. Two types of ultrasonic processing techniques were developed and attempted. The first one related to introducing the vibration into the solidifying specimen through the liquid, while the second through the formally solidified part. For the first ultrasonic processing technique, the treatment was employed isothermally, intermittently, and continuously. In contrast to the fully developed dendrites up to several millimeters in length in untreated A356 alloy, fine globular primary fcc Al grains sized less than 200 mm were obtained in the specimen treated with 5 second intermittent ultrasonic vibrations. However, dendrites were not completely broken down into fine grains in the isothermally or continuously processed specimens. It may imply that there is limited effect of dendrite fragmentation on the formation of globular/non-dendrite microstructure in the acoustically processed melt, and acoustically induced heterogeneous nucleation seems to be the dominant mechanism for the formation of a globular microstructure. For the second approach, ultrasonic treatment was performed continuously. During the treatment, grain refinement reached an unprecedented level. The average grains were globular with size ranges from 20 to 40 mm. Superfine globular grains of size less than 20 mm were obtained in the area near the ultrasonic radiator. Similar grain refinement could only be reached by using a quenching method with a much faster cooling rate. The main parameters of ultrasonic processing, such as casting temperature, ultrasonic intensity, and the distance from the radiator, have been investigated. It is concluded that high acoustic amplitude/intensity favors the formation of small, spherical primary aluminum grains. The casting temperature of 630°C brings about best grain refinement result. The primary aluminum grain size in a casting increases with the increasing distance from the acoustic radiator. In order to examine the feasibility of ultrasonic vibration for SSM processing, high intensity ultrasonic vibration has been applied during the casting of A356 alloy at high volume. Non-dendritic/globular grains have been obtained. Grain refiner can further refine A356 alloy structure, with the combination of ultrasonic vibration. Experiments on the grain refinement of other aluminum alloys have been carried out. Fine globular grains were obtained in various aluminum alloys, including A354, 319, 6063, 6061, 2618 alloys. It was found that 670 °C is the optimum casting temperature for grain refinement of 2618 with the aid of ultrasonic vibration. The effect of ultrasonic vibration on the modification of eutectic silicon in aluminum-silicon alloys has been studied. The introduction of ultrasonic vibration into A356 alloy modified the morphology of eutectic silicon from a coarse acicular plate-like form to a finely dispersed rosette-like form. The length, width, and aspect ratio of eutectic silicon all reduced significantly. This modification is beneficial to the mechanical properties. Ultrasonic grain refinement and secondary phases modification to magnesium AM60B alloy have been examined. With ultrasonic vibration, alloy experienced a reduction in size of primary α-Mg grains from 760 µm to about 25~48 µm in diameter, which is much better than other traditional grain refinement methods. The morphology of eutectic phases was modified from a mainly fully divorced blocky morphology dispersed among dendrite arms, to a mainly lamellar/script morphology across the grain boundaries. Furthermore, the volume fraction of the eutectic morphology is less. Ultrasonic processing of solidifying metals can have a number of applications. Incorporating ultrasonic vibration into a die casting machine would dramatically increase the integrity and properties of die castings. Ultrasonic vibration may be used for producing semisolid feedstock directly from molten metal. Ultrasonic techniques can also find applications in forging industries for processing alloys that are difficult to cast. Ultrasonic treatment has the advantages of being environmentally favorable, cost effective, and ready to be combined with other known physical processing technologies for liquid and solidifying metal. It is expected that the results of this study will impact a wide range of alloy processing including DC casting, continuous casting, vacuum arc remelting, and foundry processing in the areas of grain refinement, semi-solid metalcasting (SSM), and the production of new and novel microstructures. It is highly recommended to continue both the research reported in this study and the application and commercialization of this technology

Complete integrability of information processing by biochemical reactions

Statistical mechanics provides an effective framework to investigate information processing in biochemical reactions. Within such framework far-reaching analogies are established among (anti-) cooperative collective behaviors in chemical kinetics, (anti-)ferromagnetic spin models in statistical mechanics and operational amplifiers/flip-flops in cybernetics. The underlying modeling -- based on spin systems -- has been proved to be accurate for a wide class of systems matching classical (e.g. Michaelis--Menten, Hill, Adair) scenarios in the infinite-size approximation. However, the current research in biochemical information processing has been focusing on systems involving a relatively small number of units, where this approximation is no longer valid. Here we show that the whole statistical mechanical description of reaction kinetics can be re-formulated via a mechanical analogy -- based on completely integrable hydrodynamic-type systems of PDEs -- which provides explicit finite-size solutions, matching recently investigated phenomena (e.g. noise-induced cooperativity, stochastic bi-stability, quorum sensing). The resulting picture, successfully tested against a broad spectrum of data, constitutes a neat rationale for a numerically effective and theoretically consistent description of collective behaviors in biochemical reactions.Comment: 24 pages, 10 figures; accepted for publication in Scientific Report

A theory of delay-insensitive systems

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Accessing Metastable Solid-Solution Nanoparticles from Solution-Phase Condensation Reactions: Applications in High-K Dielectrics, Geopolymerization, and X-Ray Phosphors

This dissertation focuses on the design, synthesis, and functional applications of ceramic materials prepared with precise compositional, dimensional, and structural control from molecular precursors using a versatile sol—gel condensation process. Three primary thrusts have stemmed from this central idea: (i) mapping the size-dependent phase diagram of HfOv2 and stabilizing the metastable tetragonal phase of HfOv2 at room temperature as a result of dimensional confinement, thereby obtaining a technologically important high-dielectric-constant polymorph that is only accessible above a temperature of 1720°C in the bulk; (ii) developing a method to cross-link plant fibers through creation of siloxane frameworks, resulting in the stabilization of a mechanically resilient load-bearing composite for roadworks in the Alberta Oil Sands; and (iii) stabilizing solid-solution rare earth oxychloride (REOCl) nanocrystals across a broad compositional range to obtain a full palette of X-ray phosphors, allowing for elucidation of activation channels, sensitization mechanisms, and recombination pathways underpinning X-ray-activated optical luminescence. The dissertation develops a versatile synthetic toolbox for defining oxide and oxyhalide frameworks. The choice of molecular precursors and ligands added during synthesis strongly influence kinetics of particle growth and allow for compositional control as well as tunability of particle dimensions. The metastable materials synthesized in this work have allowed for exploration of the size-dependent phase diagram of HfO2 and have enabled the development of quaternary and quintary solid-solution phosphors based on the PbFCl-type LaOCl and GdOCl frameworks