Measurements, Models, Systems and Design

531 s.

Radiation Hardened by Design Methodologies for Soft-Error Mitigated Digital Architectures

abstract: Digital architectures for data encryption, processing, clock synthesis, data transfer, etc. are susceptible to radiation induced soft errors due to charge collection in complementary metal oxide semiconductor (CMOS) integrated circuits (ICs). Radiation hardening by design (RHBD) techniques such as double modular redundancy (DMR) and triple modular redundancy (TMR) are used for error detection and correction respectively in such architectures. Multiple node charge collection (MNCC) causes domain crossing errors (DCE) which can render the redundancy ineffectual. This dissertation describes techniques to ensure DCE mitigation with statistical confidence for various designs. Both sequential and combinatorial logic are separated using these custom and computer aided design (CAD) methodologies. Radiation vulnerability and design overhead are studied on VLSI sub-systems including an advanced encryption standard (AES) which is DCE mitigated using module level coarse separation on a 90-nm process with 99.999% DCE mitigation. A radiation hardened microprocessor (HERMES2) is implemented in both 90-nm and 55-nm technologies with an interleaved separation methodology with 99.99% DCE mitigation while achieving 4.9% increased cell density, 28.5 % reduced routing and 5.6% reduced power dissipation over the module fences implementation. A DMR register-file (RF) is implemented in 55 nm process and used in the HERMES2 microprocessor. The RF array custom design and the decoders APR designed are explored with a focus on design cycle time. Quality of results (QOR) is studied from power, performance, area and reliability (PPAR) perspective to ascertain the improvement over other design techniques. A radiation hardened all-digital multiplying pulsed digital delay line (DDL) is designed for double data rate (DDR2/3) applications for data eye centering during high speed off-chip data transfer. The effect of noise, radiation particle strikes and statistical variation on the designed DDL are studied in detail. The design achieves the best in class 22.4 ps peak-to-peak jitter, 100-850 MHz range at 14 pJ/cycle energy consumption. Vulnerability of the non-hardened design is characterized and portions of the redundant DDL are separated in custom and auto-place and route (APR). Thus, a range of designs for mission critical applications are implemented using methodologies proposed in this work and their potential PPAR benefits explored in detail.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

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

A Structured Design Methodology for High Performance VLSI Arrays

abstract: The geometric growth in the integrated circuit technology due to transistor scaling also with system-on-chip design strategy, the complexity of the integrated circuit has increased manifold. Short time to market with high reliability and performance is one of the most competitive challenges. Both custom and ASIC design methodologies have evolved over the time to cope with this but the high manual labor in custom and statistic design in ASIC are still causes of concern. This work proposes a new circuit design strategy that focuses mostly on arrayed structures like TLB, RF, Cache, IPCAM etc. that reduces the manual effort to a great extent and also makes the design regular, repetitive still achieving high performance. The method proposes making the complete design custom schematic but using the standard cells. This requires adding some custom cells to the already exhaustive library to optimize the design for performance. Once schematic is finalized, the designer places these standard cells in a spreadsheet, placing closely the cells in the critical paths. A Perl script then generates Cadence Encounter compatible placement file. The design is then routed in Encounter. Since designer is the best judge of the circuit architecture, placement by the designer will allow achieve most optimal design. Several designs like IPCAM, issue logic, TLB, RF and Cache designs were carried out and the performance were compared against the fully custom and ASIC flow. The TLB, RF and Cache were the part of the HEMES microprocessor.Dissertation/ThesisPh.D. Electrical Engineering 201

Enhancing Power Efficient Design Techniques in Deep Submicron Era

Excessive power dissipation has been one of the major bottlenecks for design and manufacture in the past couple of decades. Power efficient design has become more and more challenging when technology scales down to the deep submicron era that features the dominance of leakage, the manufacture variation, the on-chip temperature variation and higher reliability requirements, among others. Most of the computer aided design (CAD) tools and algorithms currently used in industry were developed in the pre deep submicron era and did not consider the new features explicitly and adequately. Recent research advances in deep submicron design, such as the mechanisms of leakage, the source and characterization of manufacture variation, the cause and models of on-chip temperature variation, provide us the opportunity to incorporate these important issues in power efficient design. We explore this opportunity in this dissertation by demonstrating that significant power reduction can be achieved with only minor modification to the existing CAD tools and algorithms. First, we consider peak current, which has become critical for circuit's reliability in deep submicron design. Traditional low power design techniques focus on the reduction of average power. We propose to reduce peak current while keeping the overhead on average power as small as possible. Second, dual Vt technique and gate sizing have been used simultaneously for leakage savings. However, this approach becomes less effective in deep submicron design. We propose to use the newly developed process-induced mechanical stress to enhance its performance. Finally, in deep submicron design, the impact of on-chip temperature variation on leakage and performance becomes more and more significant. We propose a temperature-aware dual Vt approach to alleviate hot spots and achieve further leakage reduction. We also consider this leakage-temperature dependency in the dynamic voltage scaling approach and discover that a commonly accepted result is incorrect for the current technology. We conduct extensive experiments with popular design benchmarks, using the latest industry CAD tools and design libraries. The results show that our proposed enhancements are promising in power saving and are practical to solve the low power design challenges in deep submicron era

Circuits and Systems Advances in Near Threshold Computing

Modern society is witnessing a sea change in ubiquitous computing, in which people have embraced computing systems as an indispensable part of day-to-day existence. Computation, storage, and communication abilities of smartphones, for example, have undergone monumental changes over the past decade. However, global emphasis on creating and sustaining green environments is leading to a rapid and ongoing proliferation of edge computing systems and applications. As a broad spectrum of healthcare, home, and transport applications shift to the edge of the network, near-threshold computing (NTC) is emerging as one of the promising low-power computing platforms. An NTC device sets its supply voltage close to its threshold voltage, dramatically reducing the energy consumption. Despite showing substantial promise in terms of energy efficiency, NTC is yet to see widescale commercial adoption. This is because circuits and systems operating with NTC suffer from several problems, including increased sensitivity to process variation, reliability problems, performance degradation, and security vulnerabilities, to name a few. To realize its potential, we need designs, techniques, and solutions to overcome these challenges associated with NTC circuits and systems. The readers of this book will be able to familiarize themselves with recent advances in electronics systems, focusing on near-threshold computing

An asynchronous forth microprocessor.

Ping-Ki Tsang.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 87-95).Abstracts in English and Chinese.Abstract --- p.iAcknowledgments --- p.iiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivation and Aims --- p.1Chapter 1.2 --- Contributions --- p.3Chapter 1.3 --- Overview of the Thesis --- p.4Chapter 2 --- Asynchronous Logic g --- p.6Chapter 2.1 --- Motivation --- p.6Chapter 2.2 --- Timing Models --- p.9Chapter 2.2.1 --- Fundamental-Mode Model --- p.9Chapter 2.2.2 --- Delay-Insensitive Model --- p.10Chapter 2.2.3 --- QDI and Speed-Independent Models --- p.11Chapter 2.3 --- Asynchronous Signalling Protocols --- p.12Chapter 2.3.1 --- 2-phase Handshaking Protocol --- p.12Chapter 2.3.2 --- 4-phase Handshaking Protocol --- p.13Chapter 2.4 --- Data Representations --- p.14Chapter 2.4.1 --- Dual Rail Coded Data --- p.15Chapter 2.4.2 --- Bundled Data --- p.15Chapter 2.5 --- Previous Asynchronous Processors --- p.16Chapter 2.6 --- Summary --- p.20Chapter 3 --- The MSL16 Architecture --- p.21Chapter 3.1 --- RISC Machines --- p.21Chapter 3.2 --- Stack Machines --- p.23Chapter 3.3 --- Forth and its Applications --- p.24Chapter 3.4 --- MSL16 --- p.26Chapter 3.4.1 --- Architecture --- p.28Chapter 3.4.2 --- Instruction Set --- p.30Chapter 3.4.3 --- The Datapath --- p.32Chapter 3.4.4 --- Interrupts and Exceptions --- p.33Chapter 3.4.5 --- Implementing Forth primitives --- p.34Chapter 3.4.6 --- Code Density Estimation --- p.34Chapter 3.5 --- Summary --- p.35Chapter 4 --- Design Methodology --- p.37Chapter 4.1 --- Basic Notation --- p.38Chapter 4.2 --- Specification of MSL16A --- p.39Chapter 4.3 --- Decomposition into Concurrent Processes --- p.41Chapter 4.4 --- Separation of Control and Datapath --- p.45Chapter 4.5 --- Handshaking Expansion --- p.45Chapter 4.5.1 --- 4-Phase Handshaking Protocol --- p.46Chapter 4.6 --- Production-rule Expansion --- p.47Chapter 4.7 --- Summary --- p.48Chapter 5 --- Implementation --- p.49Chapter 5.1 --- C-element --- p.49Chapter 5.2 --- Mutual Exclusion Elements --- p.51Chapter 5.3 --- Caltech Asynchronous Synthesis Tools --- p.53Chapter 5.4 --- Stack Design --- p.54Chapter 5.4.1 --- Eager Stack Control --- p.55Chapter 5.4.2 --- Lazy Stack Control --- p.56Chapter 5.4.3 --- Eager/Lazy Stack Datapath --- p.53Chapter 5.4.4 --- Pointer Stack Control --- p.61Chapter 5.4.5 --- Pointer Stack Datapath --- p.62Chapter 5.5 --- ALU Design --- p.62Chapter 5.5.1 --- The Addition Operation --- p.63Chapter 5.5.2 --- Zero-Checker --- p.64Chapter 5.6 --- Memory Interface and Tri-state Buffers --- p.64Chapter 5.7 --- MSL16A --- p.65Chapter 5.8 --- Summary --- p.66Chapter 6 --- Results --- p.67Chapter 6.1 --- FPGA based implementation of MSL16 --- p.67Chapter 6.2 --- MSL16A --- p.69Chapter 6.2.1 --- A Comparison of 3 Stack Designs --- p.69Chapter 6.2.2 --- Evaluation of the ALU --- p.73Chapter 6.2.3 --- Evaluation of MSL16A --- p.74Chapter 6.3 --- Summary --- p.81Chapter 7 --- Conclusions --- p.83Chapter 7.1 --- Future Work --- p.85Bibliography --- p.87Publications --- p.9

EFFICIENT HARDWARE PRIMITIVES FOR SECURING LIGHTWEIGHT SYSTEMS

In the era of IoT and ubiquitous computing, the collection and communication of sensitive data is increasingly being handled by lightweight Integrated Circuits. Efficient hardware implementations of crytographic primitives for resource constrained applications have become critical, especially block ciphers which perform fundamental operations such as encryption, decryption, and even hashing. We study the efficiency of block ciphers under different implementation styles. For low latency applications that use unrolled block cipher implementations, we design a glitch filter to reduce energy consumption. For lightweight applications, we design a novel architecture for the widely used AES cipher. The design eliminates inefficiencies in data movement and clock activity, thereby significantly improving energy efficiency over state-of-the-art architectures. Apart from efficiency, vulnerability to implementation attacks are a concern, which we mitigate by our randomization capable lightweight AES architecture. We fabricate our designs in a commercial 16nm FinFET technology and present measured testchip data on energy consumption and side channel resistance. Finally, we address the problem of supply chain security by using image processing techniques to extract fingerprints from surface texture of plastic IC packages for IC authentication and counterfeit prevention. Collectively these works present efficient and cost effective solutions to secure lightweight systems