5-Bit Dual-Slope Analog-to-Digital Converter-Based Time-to-Digital Converter Chip Design in CMOS Technology

Time-to-Digital Converters (TDC) have gained increasing importance in modern implementations of mixed-signal, data-acquisition and processing interfaces and are used to perform high precision time intervals in systems that incorporate Time-of-Flight (ToF) or Time-of-Arrival (ToA) measurements. The linearity of TDCs is very crucial since most Digital Signal Processing (DSP) systems require very linear inputs to achieve high accuracy. In this work, a TDC has been designed in the 0.5 μm n-well CMOS process that can be used for on-chip integration and in applications requiring high linearity. This TDC used a Dual-Slope-ADC-based architecture for the time-to-digital conversion and consists of the following three main sub-circuits: a time-to-voltage conversion part, an integrating part and digital circuitry. The design is operated with ±2.5V supply voltage and the digital circuitry, consisting of two digital counters and an adder, are operated with a clock frequency of 13MHz. The design of the TDC is discussed and simulated and experimental test results and linearity performance of the fabricated TDC are also presented

Technology independent ASIC based time to digital converter

This paper proposes a design methodology for a synthesizable, fully digital TDC architecture. The TDC was implemented using a hardware description language (HDL), which improves portability between platforms and technologies and significantly reduces design time. The proposed design flow is fully automated using TCL scripting and standard CAD tools configuration files. The TDC is based on a Tapped Delay Line architecture and explores the use of Structured Data Path (SDP) as a way to improve the TDL linearity by homogenizing the routing and parasitic capacitances across the multiple TDL’s steps. The studied approach also secures a stable, temperature independent measurement operation. The proposed TDC architecture was fabricated using TSMC 180nm CMOS process technology, with a 50MHz reference clock and a supply voltage of 1.8V. The fabricated TDC achieved an 111ps RMS resolution and a single-shot precision of 54ps (0.48 LSB) and 279ps (2.51 LSB), with and without post-measurement software calibration, respectively. The DNL across the channel is mostly under 0.3 LSB and a maximum of 8 LSB peak-to-peak INL was achieved, when no calibration is applied.- (037902

TIME-DIFFERENCE CIRCUITS: METHODOLOGY, DESIGN, AND DIGITAL REALIZATION

This thesis presents innovations for a special class of circuits called Time Difference (TD) circuits. We introduce a signal processing methodology with TD signals that alters the target signal from a magnitude perspective to time interval between two time events and systematically organizes the primary TD functions abstracted from existing TD circuits and systems. The TD circuits draw attention from a broad range of application fields. In addition, highly evolved complementary metal-oxide-semiconductor (CMOS) technology suffers from various problems related to voltage and current amplitude signal processing methods. Compared to traditional analog and digital circuits, TD circuits bring several compelling features: high-resolution, high-throughput, and low-design complexity with digital integration capability. Further, the fabrication technology is advancing into the nanometer regime; the reduction in voltage headroom limits the performance of traditional analog/mixed-signal designs. All-digital design of time-difference circuit needs to be stressed to adapt to the low-cost, low-power, and high-portability applications. We focus on Time-to-Digital Converters (TDC), one of the crucial building blocks in TD circuits. A novel algorithmic architecture is proposed based on a binary search algorithm and validated with both simulation and fabricated silicon. An all-digital structure Time-difference Amplifier (TDA) is designed and implemented to make FPGA and other all-digital implementations for TDC and related TD circuits feasible. Besides, we propose an all-digital timing measurement circuit based on the process variation from CMOS fabrication: PVTMC, which achieves a high measurement resolution:

Bioinformatic analysis of genome-scale data reveals insights into host-pathogen interactions in farm animals

This thesis documents the contribution of my bioinformatics research activities, including novel software development, to a range of research projects aimed at investigating the interactions between bacterial and viral pathogens and their hosts. The focus is largely on farm animal species and their pathogens, although some of the research has a wider scientific impact. RNA interference (RNAi) refers to a variety of related regulatory pathways present in animals, plants and insects. The major pathways are microRNAs (miRNAs), small-interfering RNAs (siRNAs) and PIWI-interacting RNAs (piRNAs). Marek’s disease virus is an important pathogen of poultry, causing T-cell lymphoma. We identified the presence and expression patterns of several MDV-encoded microRNAs, including the identification of 5 novel microRNAs. We also showed that not only do virus-encoded microRNAs dominate the mirNome within chicken cells, but also that specific host-microRNAs are down-regulated. We also identify novel virus-encoded microRNAs in other Herpesviridae and provide the first evidence of miRNA evolution by duplication in viruses. In related work, we present a novel microRNA generated by the canonical miRNA biogenesis pathway in Avian Leukosis Virus, another avian oncogenic virus, and publish data showing the expression pattern of known chicken microRNAs across a range of important avian cells. Two of the other RNAi pathways (siRNA and piRNA) form an important part of the antiviral response in arthropods. We have published work demonstrating an siRNA antiviral response to bluetongue virus and Schmallenberg virus in cells from the Culicoides midge, an important insect vector, as well as work demonstrating the importance of the piRNA pathway in the antiviral response to Semliki forest virus (SFV). Further work on flaviviruses in ticks demonstrates the active suppression of the siRNA response by Langat Virus, as well as a key difference between the siRNA responses in Mosquitos compared to ticks. Salmonella is one of the most important zoonoses, with an estimated 1.4 million cases of human salmonellosis per annum in the USA alone. Salmonella infections of farm animals are an important route into the human food chain. This thesis presents work on the comparative structure and function of 13 fimbrial operons within Salmonella enterica serovar Enteritidis as well as a genomic comparison of that serovar with Salmonella enterica serovar Gallinarum, a chicken-specific serovar. We characterised the global expression profile of Salmonella enterica serovar Typhimurium during colonization of the chicken intestine, and we have published the genomes of four strains of Salmonella eneterica serovars of well-defined virulence in food-producing animals. Our work in this area led to us publishing an important and comprehensive review of the automatic annotation of bacterial genomes. Finally, I present work on novel software development. ProGenExpress, a software tool that allows the easy and accurate integration and visualisation of quantitative data with the genome annotation of bacteria; Meta4 is a web application that allows data sharing of bacterial genome annotations from metagenomes; CORNA, a software tool that allows scientists to link together microRNA targets, gene expression and functional annotation; viRome, a software tool for the analysis of siRNA and piRNA responses in virus-infection studies; DetectiV, a software tool for the analysis of pathogen-detection microarray data; and poRe, a software tool that enables users to organise and analyse nanopore sequencing dat