A framework for fine-grain synthesis optimization of operational amplifiers

This thesis presents a cell-level framework for Operational Amplifiers Synthesis (OASYN) coupling both circuit design and layout. For circuit design, the tool applies a corner-driven optimization, accounting for on-chip performance variations. By exploring the process, voltage, and temperature variations space, the tool extracts design worst case solution. The tool undergoes sensitivity analysis along with Pareto-optimality to achieve required specifications. For layout phase, OASYN generates a DRC proved automated layout based on a sized circuit-level description. Morata et al. (1996) introduced an elegant representation of block placement called sequence pair for general floorplans (SP). Like TCG and BSG, but unlike O-tree, B*tree, and CBL, SP is P-admissible. Unlike SP, TCG supports incremental update during operation and keeps the information of the boundary modules as well as their relative positions in the representation. Block placement algorithms that are based on SP use heuristic optimization algorithms, e.g., simulated annealing where generation of large number of sequence pairs are required. Therefore a fast algorithm is needed to generate sequence pairs after each solution perturbation. The thesis presents a new simple and efficient O(n) runtime algorithm for fast realization of incremental update for cost evaluation. The algorithm integrates sequence pair and transitive closure graph advantages into TCG-S* a superior topology update scheme which facilitates the search for optimum desired floorplan. Experiments show that TCG-S* is better than existing works in terms of area utilization and convergence speed. Routing-aware placement is implemented in OASYN, handling symmetry constraints, e.g., interdigitization, common centroid, along with congestion elimination and the enhancement of placement routability

Placement techniques in automatic analog layout generation.

模擬電路版圖設計是一個非常複雜和耗時的過程。通常情況下，設計一個高質量的模擬電路版圖需要電子工程師花費幾週甚至更長的時間。模擬電路的電子特性對於電路的細節設計非常敏感，因此，減小電路中的失配現象成為模擬電路版圖設計中一個非常重要的課題。在本論文中，我們提出了一系列實際的佈局技術，來降低電路的失配並提高繞線的成功率。我們可以非常容易的將這些技術整合至一個完整的模擬佈局和佈線的工具中，此工具可以在幾分鐘內生成一個完整的、高質量的模擬電路版圖。同時，該版圖能夠通過設計規則驗證（DRC）和佈局與電路設計一致性檢測（LVS）。模擬結果顯示，它的電路性能能夠與達到甚至超出手工設計的電路版圖。我們的論文主要作出了以下兩方面貢獻。1. 平衡佈局：對於模擬電路中的電子元器件，如電容、電阻、晶體管等進行一維和二維的平衡佈局。電子工程師可以根據不同的設計需求，通過選擇不同的佈局參數來改變電路的佈局排列方式。同時，在模擬退火算法中，我們著重考慮了器件間的匹配以生成高質量的模擬電路佈局。2. 消除阻塞的電路佈局：在模擬電路設計中，我們期望盡量避免在電子元器件密度較高的區域進行繞線。因此，我們需要在電路佈局設計過程中在電子元器件間留有足夠的佈線空間。為達到這個目標，我們提出了更精確的阻塞估計方法和版圖拓展方法，使其能夠生成一個高質量、高繞線成功率的電路佈局結果。為了驗證生成的電路版圖的質量和匹配特性，我們利用蒙地卡羅方法來模擬電路中的製程偏差和失配特性。實驗結果顯示，我們的工具可以在幾分鐘內自動生成高質量的電路版圖，與人工設計通常需要花費數日至數週相比，設計時間大幅縮短，同時電路的匹配特性得以提升。Analog layout design is a complicated and time-consuming process. It often takes couples of weeks for the layout designers to generate a qualied layout. The elec-trical properties of analog circuit are very sensitive to the layout details, and mis-match reduction becomes a very important issue in analog layout design.In this thesis, we will present some practical placement techniques to reduce mismatch and improve routability. These techniques can be easily integrated into a complete analog placement and routing ow, which can produce in just a few min-utes a complete and high quality layout for analog circuits that passes the design rule check, layout-schematic check and with performance veried by simulations. The contents of this thesis will focus on the following two issues:(1) Symmetry Placement: We consider symmetric placement of transistors, re-sistors and capacitors, which includes 1-D symmetry and 2-D symmetry (or called common centroid). Different symmetric placement congurations, derived accord-ing to the practical needs in analog design, are considered for the matching devices in the simulated annealing engine of the placer in order to generate a placement with high quality.(2) Congestion-driven Placement: In analog design, wires are preferred not be routed over active devices, so we need to leave enough spaces properly for routing between the devices during the placement process. To achieve this, we explore congestion estimation and layout expansion during the placement step in order to produce a good and routable solution.In order to verify the quality of the generated layouts in terms of mismatch, we will run Monte Carlo simulations on them with variations in process and mismatch. Experiments show that our methodology can generate high quality layout automatically in just a few minutes while manual design may take couples of days.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Cui, Guxin.Thesis (M.Phil.)--Chinese University of Hong Kong, 2012.Abstracts also in Chinese.Abstract --- p.iAcknowledgement --- p.ivChapter 1 --- Introduction --- p.1Chapter 1.1 --- Background --- p.1Chapter 1.2 --- Physical Design --- p.2Chapter 1.3 --- Analog Placement --- p.4Chapter 1.3.1 --- Methodologies of Analog Placement --- p.4Chapter 1.3.2 --- Symmetry Constraints of Analog Placement --- p.5Chapter 1.4 --- Process Variation and Layout Mismatch --- p.6Chapter 1.4.1 --- Process Variation --- p.6Chapter 1.4.2 --- Random Mismatch and Systematic Mismatch --- p.7Chapter 1.5 --- Monte Carlo Simulation Procedure --- p.9Chapter 1.6 --- Problem Formulation of Placement --- p.9Chapter 1.7 --- Motivations --- p.10Chapter 1.8 --- Contributions --- p.11Chapter 1.9 --- Thesis Organization --- p.12Chapter 2 --- Literature Review on Analog Placement --- p.13Chapter 2.1 --- Topological Representations Handling Symmetry Constraints --- p.14Chapter 2.1.1 --- Symmetry within the Sequence-Pair (SP) Representation . --- p.14Chapter 2.1.2 --- Block Placement with Symmetry Constraints Based on the O-Tree Non-Slicing Representation --- p.16Chapter 2.1.3 --- Placement with Symmetry Constraints for Analog Layout Design Using TCG-S --- p.17Chapter 2.1.4 --- Modeling Non-Slicing Floorplans with Binary Trees --- p.19Chapter 2.1.5 --- Segment Trees Handle Symmetry Constraints --- p.20Chapter 2.1.6 --- Center-based Corner Block List --- p.22Chapter 2.2 --- Other Works on Analog Placement Constraints --- p.25Chapter 2.2.1 --- Deterministic Analog Placement with Hierarchically Bounded Enumeration and Enhanced Shape Functions --- p.25Chapter 2.2.2 --- Analog Placement Based on Symmetry-Island Formulation --- p.27Chapter 2.2.3 --- Heterogeneous B*-Trees for Analog Placement with Symmetry and Regularity Considerations --- p.28Chapter 2.3 --- Summary --- p.31Chapter 3 --- Common-Centroid Analog Placement --- p.32Chapter 3.1 --- Problem Formulation --- p.33Chapter 3.2 --- Overview of Our Work --- p.35Chapter 3.3 --- Handling Common Centroid Constraints in Different Devices --- p.37Chapter 3.3.1 --- Common Centroid Placement of Resistors --- p.38Chapter 3.3.2 --- Common Centroid Placement of Transistors --- p.44Chapter 3.3.3 --- Common Centroid Placement of Capacitors --- p.47Chapter 3.4 --- Congestion Estimation and Layout Expansion --- p.50Chapter 3.4.1 --- Blockage-Aware Congestion Estimation --- p.51Chapter 3.4.2 --- Layout Expansion --- p.56Chapter 3.5 --- Simulated Annealing --- p.59Chapter 3.5.1 --- Types of Moves --- p.59Chapter 3.5.2 --- Handling Devices in Symmetry Group --- p.59Chapter 3.5.3 --- Cost Function of Simulated Annealing --- p.61Chapter 3.6 --- Summary --- p.62Chapter 4 --- Experimental Results and Monte-Carlo Simulations --- p.64Chapter 4.1 --- Study of Congestion-driven Layout Expansion --- p.64Chapter 4.2 --- Monte Carlo Simulations --- p.70Chapter 4.2.1 --- Devices Modeling --- p.70Chapter 4.2.2 --- Study of Layouts with and without Symmetry Groups --- p.71Chapter 4.2.3 --- Study of Layouts with and without Self-Symmetry Devices --- p.73Chapter 4.2.4 --- Study of Layouts with Different Number of Symmetry Groups --- p.74Chapter 4.2.5 --- Study of Large and Small Size Capacitors Array --- p.76Chapter 4.3 --- Comparison of Automatic and Manual Layouts using Monte Carlo Simulations --- p.79Chapter 5 --- Conclusion --- p.86Bibliography --- p.8

Physical Planning and Uncore Power Management for Multi-Core Processors

For the microprocessor technology of today and the foreseeable future, multi-core is a key engine that drives performance growth under very tight power dissipation constraints. While previous research has been mostly focused on individual processor cores, there is a compelling need for studying how to efficiently manage shared resources among cores, including physical space, on-chip communication and on-chip storage. In managing physical space, floorplanning is the first and most critical step that largely affects communication efficiency and cost-effectiveness of chip designs. We consider floorplanning with regularity constraints that requires identical processing/memory cores to form an array. Such regularity can greatly facilitate design modularity and therefore shorten design turn-around time. Very little attention has been paid to automatic floorplanning considering regularity constraints because manual floorplanning has difficulty handling the complexity as chip core count increases. In this dissertation work, we investigate the regularity constraints in a simulated-annealing based floorplanner for multi/many core processor designs. A simple and effective technique is proposed to encode the regularity constraints in sequence-pair, which is a classic format of data representation in automatic floorplanning. To the best of our knowledge, this is the first work on regularity-constrained floorplanning in the context of multi/many core processor designs. On-chip communication and shared last level cache (LLC) play a role that is at least as equally important as processor cores in terms of chip performance and power. This dissertation research studies dynamic voltage and frequency scaling for on-chip network and LLC, which forms a single uncore domain of voltage and frequency. This is in contrast to most previous works where the network and LLC are partitioned and associated with processor cores based on physical proximity. The single shared domain can largely avoid the interfacing overhead across domain boundaries and is practical and very useful for industrial products. Our goal is to minimize uncore energy dissipation with little, e.g., 5% or less, performance degradation. The first part of this study is to identify a metric that can reflect the chip performance determined by uncore voltage/frequency. The second part is about how to monitor this metric with low overhead and high fidelity. The last part is the control policy that decides uncore voltage/frequency based on monitoring results. Our approach is validated through full system simulations on public architecture benchmarks

Scalability and interconnection issues in floorplan design and floorplan representations.

Yuen Wing-seung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.Includes bibliographical references (leaves [116]-[122]).Abstracts in English and Chinese.Abstract --- p.iAcknowledgments --- p.iiiList of Figures --- p.viiiList of Tables --- p.xiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivations and Aims --- p.1Chapter 1.2 --- Contributions --- p.3Chapter 1.3 --- Dissertation Overview --- p.4Chapter 2 --- Physical Design and Floorplanning in VLSI Circuits --- p.6Chapter 2.1 --- VLSI Design Flow --- p.6Chapter 2.2 --- Floorplan Design --- p.8Chapter 2.2.1 --- Problem Formulation --- p.9Chapter 2.2.2 --- Types of Floorplan --- p.10Chapter 3 --- Floorplanning Representations --- p.12Chapter 3.1 --- Polish Expression(PE) [WL86] --- p.12Chapter 3.2 --- Bounded-Sliceline-Grid(BSG) [NFMK96] --- p.14Chapter 3.3 --- Sequence Pair(SP) [MFNK95] --- p.17Chapter 3.4 --- O-tree(OT) [GCY99] --- p.19Chapter 3.5 --- B*-tree(BT) [CCWW00] --- p.21Chapter 3.6 --- Corner Block List(CBL) [HHC+00] --- p.22Chapter 4 --- Optimization Technique in Floorplan Design --- p.27Chapter 4.1 --- General Optimization Methods --- p.27Chapter 4.1.1 --- Simulated Annealing --- p.27Chapter 4.1.2 --- Genetic Algorithm --- p.29Chapter 4.1.3 --- Integer Programming Method --- p.31Chapter 4.2 --- Shape Optimization --- p.33Chapter 4.2.1 --- Shape Curve --- p.33Chapter 4.2.2 --- Lagrangian Relaxation --- p.34Chapter 5 --- Literature Review on Interconnect Driven Floorplanning --- p.37Chapter 5.1 --- Placement Constraint in Floorplan Design --- p.37Chapter 5.1.1 --- Boundary Constraints --- p.37Chapter 5.1.2 --- Pre-placed Constraints --- p.39Chapter 5.1.3 --- Range Constraints --- p.41Chapter 5.1.4 --- Symmetry Constraints --- p.42Chapter 5.2 --- Timing Analysis Method --- p.43Chapter 5.3 --- Buffer Block Planning and Congestion Control --- p.45Chapter 5.3.1 --- Buffer Block Planning --- p.45Chapter 5.3.2 --- Congestion Control --- p.50Chapter 6 --- Clustering Constraint in Floorplan Design --- p.53Chapter 6.1 --- Problem Definition --- p.53Chapter 6.2 --- Overview --- p.54Chapter 6.3 --- Locating Neighboring Modules --- p.56Chapter 6.4 --- Constraint Satisfaction --- p.62Chapter 6.5 --- Multi-clustering Extension --- p.64Chapter 6.6 --- Cost Function --- p.64Chapter 6.7 --- Experimental Results --- p.65Chapter 7 --- Interconnect Driven Multilevel Floorplanning Approach --- p.69Chapter 7.1 --- Multilevel Partitioning --- p.69Chapter 7.1.1 --- Coarsening Phase --- p.70Chapter 7.1.2 --- Refinement Phase --- p.70Chapter 7.2 --- Overview of Multilevel Floorplanner --- p.72Chapter 7.3 --- Clustering Phase --- p.73Chapter 7.3.1 --- Clustering Methods --- p.73Chapter 7.3.2 --- Area Ratio Constraints --- p.75Chapter 7.3.3 --- Clustering Velocity --- p.76Chapter 7.4 --- Refinement Phase --- p.77Chapter 7.4.1 --- Temperature Control --- p.79Chapter 7.4.2 --- Cost Function --- p.80Chapter 7.4.3 --- Handling Shape Flexibility --- p.80Chapter 7.5 --- Experimental Results --- p.81Chapter 7.5.1 --- Data Set Generation --- p.82Chapter 7.5.2 --- Temperature Control --- p.82Chapter 7.5.3 --- Packing Results --- p.83Chapter 8 --- Study of Non-slicing Floorplan Representations --- p.89Chapter 8.1 --- Analysis of Different Floorplan Representations --- p.89Chapter 8.1.1 --- Complexity --- p.90Chapter 8.1.2 --- Types of Floorplans --- p.92Chapter 8.2 --- T-junction Orientation Property --- p.97Chapter 8.3 --- Twin Binary Tree Representation for Mosaic Floorplan --- p.103Chapter 8.3.1 --- Previous work --- p.103Chapter 8.3.2 --- Twin Binary Tree Construction --- p.105Chapter 8.3.3 --- Floorplan Construction --- p.109Chapter 9 --- Conclusion --- p.114Chapter 9.1 --- Summary --- p.114Bibliography --- p.116Chapter A --- Clustering Constraint Data Set --- p.123Chapter A.1 --- ami33 --- p.123Chapter A.1.1 --- One cluster --- p.123Chapter A.1.2 --- Multi-cluster --- p.123Chapter A.2 --- ami49 --- p.124Chapter A.2.1 --- One cluster --- p.124Chapter A.2.2 --- Multi-cluster --- p.124Chapter A.3 --- playout --- p.124Chapter A.3.1 --- One cluster --- p.124Chapter A.3.2 --- Multi-cluster --- p.125Chapter B --- Multilevel Data Set --- p.126Chapter B.l --- data_100 --- p.126Chapter B.2 --- data_200 --- p.127Chapter B.3 --- data_300 --- p.129Chapter B.4 --- data_400 --- p.131Chapter B.5 --- data_500 --- p.13

Interconnect Planning for Physical Design of 3D Integrated Circuits

Vertical stacking—based on modern manufacturing and integration technologies—of multiple 2D chips enables three-dimensional integrated circuits (3D ICs). This exploitation of the third dimension is generally accepted for aiming at higher packing densities, heterogeneous integration, shorter interconnects, reduced power consumption, increased data bandwidth, and realizing highly-parallel systems in one device. However, the commercial acceptance of 3D ICs is currently behind its expectations, mainly due to challenges regarding manufacturing and integration technologies as well as design automation. This work addresses three selected, practically relevant design challenges: (i) increasing the constrained reusability of proven, reliable 2D intellectual property blocks, (ii) planning different types of (comparatively large) through-silicon vias with focus on their impact on design quality, as well as (iii) structural planning of massively-parallel, 3D-IC-specific interconnect structures during 3D floorplanning. A key concept of this work is to account for interconnect structures and their properties during early design phases in order to support effective and high-quality 3D-IC-design flows. To tackle the above listed challenges, modular design-flow extensions and methodologies have been developed. Experimental investigations reveal the effectiveness and efficiency of the proposed techniques, and provide findings on 3D integration with particular focus on interconnect structures. We suggest consideration of these findings when formulating guidelines for successful 3D-IC design automation.:1 Introduction 1.1 The 3D Integration Approach for Electronic Circuits 1.2 Technologies for 3D Integrated Circuits 1.3 Design Approaches for 3D Integrated Circuits 2 State of the Art in Design Automation for 3D Integrated Circuits 2.1 Thermal Management 2.2 Partitioning and Floorplanning 2.3 Placement and Routing 2.4 Power and Clock Delivery 2.5 Design Challenges 3 Research Objectives 4 Planning Through-Silicon Via Islands for Block-Level Design Reuse 4.1 Problems for Design Reuse in 3D Integrated Circuits 4.2 Connecting Blocks Using Through-Silicon Via Islands 4.2.1 Problem Formulation and Methodology Overview 4.2.2 Net Clustering 4.2.3 Insertion of Through-Silicon Via Islands 4.2.4 Deadspace Insertion and Redistribution 4.3 Experimental Investigation 4.3.1 Wirelength Estimation 4.3.2 Configuration 4.3.3 Results and Discussion 4.4 Summary and Conclusions 5 Planning Through-Silicon Vias for Design Optimization 5.1 Deadspace Requirements for Optimized Planning of Through-Silicon Vias 5.2 Multiobjective Design Optimization of 3D Integrated Circuits 5.2.1 Methodology Overview and Configuration 5.2.2 Techniques for Deadspace Optimization 5.2.3 Design-Quality Analysis 5.2.4 Planning Different Types of Through-Silicon Vias 5.3 Experimental Investigation 5.3.1 Configuration 5.3.2 Results and Discussion 5.4 Summary and Conclusions 6 3D Floorplanning for Structural Planning of Massive Interconnects 6.1 Block Alignment for Interconnects Planning in 3D Integrated Circuits 6.2 Corner Block List Extended for Block Alignment 6.2.1 Alignment Encoding 6.2.2 Layout Generation: Block Placement and Alignment 6.3 3D Floorplanning Methodology 6.3.1 Optimization Criteria and Phases and Related Cost Models 6.3.2 Fast Thermal Analysis 6.3.3 Layout Operations 6.3.4 Adaptive Optimization Schedule 6.4 Experimental Investigation 6.4.1 Configuration 6.4.2 Results and Discussion 6.5 Summary and Conclusions 7 Research Summary, Conclusions, and Outlook Dissertation Theses Notation Glossary BibliographyDreidimensional integrierte Schaltkreise (3D-ICs) beruhen auf neuartigen Herstellungs- und Integrationstechnologien, wobei vor allem “klassische” 2D-ICs vertikal zu einem neuartigen 3D-System gestapelt werden. Dieser Ansatz zur Erschließung der dritten Dimension im Schaltkreisentwurf ist nach Expertenmeinung dazu geeignet, höhere Integrationsdichten zu erreichen, heterogene Integration zu realisieren, kürzere Verdrahtungswege zu ermöglichen, Leistungsaufnahmen zu reduzieren, Datenübertragungsraten zu erhöhen, sowie hoch-parallele Systeme in einer Baugruppe umzusetzen. Aufgrund von technologischen und entwurfsmethodischen Schwierigkeiten bleibt jedoch bisher die kommerzielle Anwendung von 3D-ICs deutlich hinter den Erwartungen zurück. In dieser Arbeit werden drei ausgewählte, praktisch relevante Problemstellungen der Entwurfsautomatisierung von 3D-ICs bearbeitet: (i) die Verbesserung der (eingeschränkten) Wiederverwendbarkeit von zuverlässigen 2D-Intellectual-Property-Blöcken, (ii) die komplexe Planung von verschiedenartigen, verhältnismäßig großen Through-Silicion Vias unter Beachtung ihres Einflusses auf die Entwurfsqualität, und (iii) die strukturelle Einbindung von massiv-parallelen, 3D-IC-spezifischen Verbindungsstrukturen während der Floorplanning-Phase. Das Ziel dieser Arbeit besteht darin, Verbindungsstrukturen mit deren wesentlichen Eigenschaften bereits in den frühen Phasen des Entwurfsprozesses zu berücksichtigen. Dies begünstigt einen qualitativ hochwertigen Entwurf von 3D-ICs. Die in dieser Arbeit vorgestellten modularen Entwurfsprozess-Erweiterungen bzw. -Methodiken dienen zur effizienten Lösung der oben genannten Problemstellungen. Experimentelle Untersuchungen bestätigen die Wirksamkeit sowie die Effektivität der erarbeiten Methoden. Darüber hinaus liefern sie praktische Erkenntnisse bezüglich der Anwendung von 3D-ICs und der Planung deren Verbindungsstrukturen. Diese Erkenntnisse sind zur Ableitung von Richtlinien für den erfolgreichen Entwurf von 3D-ICs dienlich.:1 Introduction 1.1 The 3D Integration Approach for Electronic Circuits 1.2 Technologies for 3D Integrated Circuits 1.3 Design Approaches for 3D Integrated Circuits 2 State of the Art in Design Automation for 3D Integrated Circuits 2.1 Thermal Management 2.2 Partitioning and Floorplanning 2.3 Placement and Routing 2.4 Power and Clock Delivery 2.5 Design Challenges 3 Research Objectives 4 Planning Through-Silicon Via Islands for Block-Level Design Reuse 4.1 Problems for Design Reuse in 3D Integrated Circuits 4.2 Connecting Blocks Using Through-Silicon Via Islands 4.2.1 Problem Formulation and Methodology Overview 4.2.2 Net Clustering 4.2.3 Insertion of Through-Silicon Via Islands 4.2.4 Deadspace Insertion and Redistribution 4.3 Experimental Investigation 4.3.1 Wirelength Estimation 4.3.2 Configuration 4.3.3 Results and Discussion 4.4 Summary and Conclusions 5 Planning Through-Silicon Vias for Design Optimization 5.1 Deadspace Requirements for Optimized Planning of Through-Silicon Vias 5.2 Multiobjective Design Optimization of 3D Integrated Circuits 5.2.1 Methodology Overview and Configuration 5.2.2 Techniques for Deadspace Optimization 5.2.3 Design-Quality Analysis 5.2.4 Planning Different Types of Through-Silicon Vias 5.3 Experimental Investigation 5.3.1 Configuration 5.3.2 Results and Discussion 5.4 Summary and Conclusions 6 3D Floorplanning for Structural Planning of Massive Interconnects 6.1 Block Alignment for Interconnects Planning in 3D Integrated Circuits 6.2 Corner Block List Extended for Block Alignment 6.2.1 Alignment Encoding 6.2.2 Layout Generation: Block Placement and Alignment 6.3 3D Floorplanning Methodology 6.3.1 Optimization Criteria and Phases and Related Cost Models 6.3.2 Fast Thermal Analysis 6.3.3 Layout Operations 6.3.4 Adaptive Optimization Schedule 6.4 Experimental Investigation 6.4.1 Configuration 6.4.2 Results and Discussion 6.5 Summary and Conclusions 7 Research Summary, Conclusions, and Outlook Dissertation Theses Notation Glossary Bibliograph

Energy Reduction Techniques to Increase Battery Life for Electronic Sensor Nodes

Preserving battery life in duty-cycled sensor nodes requires minimizing energy use in the active region. Lowering the power supply of CMOS gates down into sub-threshold mode is a good way to decrease energy. In this work, a unique technique to control the current in CMOS gates to reliably operate them in sub-threshold mode is described. Compared to the current state-of-theart for running digital gates in the sub-threshold regime, this work is often superior in its lack of complexity and in reduced variance in delay caused by process variations. In addition to presenting the design considerations, a demonstration of a complete digital design flow is given using the custom gates. An AES128 encryption/decryption engine is designed using the aforementioned digital flow in a commercial 180nm process. The resulting design has a ratio of maximum to minimum frequency variation over corners of only 50% with a 0.3V power supply where the same ratio with standard CMOS gates biased under the same supply voltage is 5600%. In addition, the custom gates are used to design a Wallace tree multiplier in an SOI 45nm process that is fully functional with an optimum energy power supply level of 0.34V with a typical operating frequency of 8 MHz having a variation over corners of 80%. For a proof of concept memory chip designed in this work, the architecture uses a logiccompatible CMOS process particularly suitable for embedded applications. The differential pair construct causes the read and refresh power to be independent of any process parameter including the within-die threshold voltage. The current stop feature keeps the read voltage transition low to further minimize read power. The bit cell operates in both single bit BASE2 and multi-bit BASE4 modes. An expression for the read signal was verified with bit cell simulations. These simulations also compare the performance impact of threshold voltage variance in the architecture with a standard gain cell. A DRAM bit cell array was fabricated in the XFab 180nm CMOS process. Measured waveforms closely match theoretical results obtained from a system simulation. The silicon retention time was measured at room temperature and is greater than 150 ms in BASE2 mode and greater than 75 ms in BASE4 mode. 180nm, 25C analysis predicts 0.8uW/Mbit refresh power at 630 MHz, the lowest in the literature. Further: the memory bit cell architecture presented here has a refresh power delay product several times lower than any other published architecture. The current controlled memory architecture in this work improves or overcomes the drawbacks of the 1T1C and gain cell memory architectures. A current controlled memory design was fabricated as a 131K bit array in an 180nm process to provide silicon proof. The bit cell configuration with shared read and write bit cells gives effectively two memory banks. The grouping of rows together into common source domains allows only two opamps to control the current in all the bit cells across the whole chip. The sense amplifiers have a globally controlled switching threshold point and keep their static power in the nano-amp range. The bit cells can operate either in BASE2 or BASE4 mode and the read bit line transitions are reduced with a current stop construct. Parts were received from the foundry in an 84-pin PLCC and were tested at a number of locations on the die. They proved to be fully functional in BASE4. The silicon retention time was measured at room temperature and was greater than four seconds

An integrated circuit biosensor for hyperthermia cancer treatment

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (p. 87-90).by Tracy Elizabeth Adams.M.Eng

Robust Design of Variation-Sensitive Digital Circuits

The nano-age has already begun, where typical feature dimensions are smaller than 100nm. The operating frequency is expected to increase up to 12 GHz, and a single chip will contain over 12 billion transistors in 2020, as given by the International Technology Roadmap for Semiconductors (ITRS) initiative. ITRS also predicts that the scaling of CMOS devices and process technology, as it is known today, will become much more difficult as the industry advances towards the 16nm technology node and further. This aggressive scaling of CMOS technology has pushed the devices to their physical limits. Design goals are governed by several factors other than power, performance and area such as process variations, radiation induced soft errors, and aging degradation mechanisms. These new design challenges have a strong impact on the parametric yield of nanometer digital circuits and also result in functional yield losses in variation-sensitive digital circuits such as Static Random Access Memory (SRAM) and flip-flops. Moreover, sub-threshold SRAM and flip-flops circuits, which are aggravated by the strong demand for lower power consumption, show larger sensitivity to these challenges which reduces their robustness and yield. Accordingly, it is not surprising that the ITRS considers variability and reliability as the most challenging obstacles for nanometer digital circuits robust design. Soft errors are considered one of the main reliability and robustness concerns in SRAM arrays in sub-100nm technologies due to low operating voltage, small node capacitance, and high packing density. The SRAM arrays soft errors immunity is also affected by process variations. We develop statistical design-oriented soft errors immunity variations models for super-threshold and sub-threshold SRAM cells accounting for die-to-die variations and within-die variations. This work provides new design insights and highlights the important design knobs that can be used to reduce the SRAM cells soft errors immunity variations. The developed models are scalable, bias dependent, and only require the knowledge of easily measurable parameters. This makes them useful in early design exploration, circuit optimization as well as technology prediction. The derived models are verified using Monte Carlo SPICE simulations, referring to an industrial hardware-calibrated 65nm CMOS technology. The demand for higher performance leads to very deep pipelining which means that hundreds of thousands of flip-flops are required to control the data flow under strict timing constraints. A violation of the timing constraints at a flip-flop can result in latching incorrect data causing the overall system to malfunction. In addition, the flip-flops power dissipation represents a considerable fraction of the total power dissipation. Sub-threshold flip-flops are considered the most energy efficient solution for low power applications in which, performance is of secondary importance. Accordingly, statistical gate sizing is conducted to different flip-flops topologies for timing yield improvement of super-threshold flip-flops and power yield improvement of sub-threshold flip-flops. Following that, a comparative analysis between these flip-flops topologies considering the required overhead for yield improvement is performed. This comparative analysis provides useful recommendations that help flip-flops designers on selecting the best flip-flops topology that satisfies their system specifications while taking the process variations impact and robustness requirements into account. Adaptive Body Bias (ABB) allows the tuning of the transistor threshold voltage, Vt, by controlling the transistor body voltage. A forward body bias reduces Vt, increasing the device speed at the expense of increased leakage power. Alternatively, a reverse body bias increases Vt, reducing the leakage power but slowing the device. Therefore, the impact of process variations is mitigated by speeding up slow and less leaky devices or slowing down devices that are fast and highly leaky. Practically, the implementation of the ABB is desirable to bias each device in a design independently, to mitigate within-die variations. However, supplying so many separate voltages inside a die results in a large area overhead. On the other hand, using the same body bias for all devices on the same die limits its capability to compensate for within-die variations. Thus, the granularity level of the ABB scheme is a trade-off between the within-die variations compensation capability and the associated area overhead. This work introduces new ABB circuits that exhibit lower area overhead by a factor of 143X than that of previous ABB circuits. In addition, these ABB circuits are resolution free since no digital-to-analog converters or analog-to-digital converters are required on their implementations. These ABB circuits are adopted to high performance critical paths, emulating a real microprocessor architecture, for process variations compensation and also adopted to SRAM arrays, for Negative Bias Temperature Instability (NBTI) aging and process variations compensation. The effectiveness of the new ABB circuits is verified by post layout simulation results and test chip measurements using triple-well 65nm CMOS technology. The highly capacitive nodes of wide fan-in dynamic circuits and SRAM bitlines limit the performance of these circuits. In addition, process variations mitigation by statistical gate sizing increases this capacitance further and fails in achieving the target yield improvement. We propose new negative capacitance circuits that reduce the overall parasitic capacitance of these highly capacitive nodes. These negative capacitance circuits are adopted to wide fan-in dynamic circuits for timing yield improvement up to 99.87% and to SRAM arrays for read access yield improvement up to 100%. The area and power overheads of these new negative capacitance circuits are amortized over the large die area of the microprocessor and the SRAM array. The effectiveness of the new negative capacitance circuits is verified by post layout simulation results and test chip measurements using 65nm CMOS technology

Local energy management through mathematical modeling and optimization

Thesis (Ph. D.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center, 2004.Includes bibliographical references (p. 217-223).(cont.) Extensions to the core TOTEM model include a demand charge model, used for making daily optimal control decisions when the electric bill includes a charge based on the monthly maximum power draw. The problem of heating, ventilation, and air conditioning (HVAC) control is treated separately since it strongly violates TOTEM's linearity assumptions. Nonetheless, we describe a solution approach to the HVAC problem which operates in conjunction with TOTEM. We also provide an analysis of storage suitability in stochastic supply and demand networks. The node-based approach lends itself well to a software system that uses a drag- and-drop graphical network creation tool. We present a graphical user interface, the XML data representation, and the communication links to and from optimization software.We develop an extensive yet tractable framework for analyzing and optimally controlling local energy networks. A local energy network is any set of generation, storage, and end-use devices existing to provide energy fulfillment to a building, a group of jointly operated buildings, or a village power system. The software developed is called TOTEM for Total Energy Management, and provides hourly (or sub-hourly) control over the flows in such energy networks. TOTEM manages multiple energy flows such as electricity, chilled water, heat, and steam together, since such energies are often coupled, particularly for networks containing cogeneration turbines (which produce electricity and steam) and absorption chillers (which use steam for driving refrigeration turbines). Due to the large number of interconnected devices in such networks, the model is kept as a linear mixed integer program, able to be solved rapidly with off-the-shelf mathematical optimization packages. Certain nonlinearities, for example input-output relationships for generators, are handled in this linear framework with piecewise linear approximations. Modeling flexibility is achieved by taking a node-centric approach. Each device in the network is represented as a node, and depending on each node's set membership, proper constraint and objective equations are written. Given the network, TOTEM uses hourly electricity and fuel pricing, weather, and demand projections to determine the optimal operating and scheduling strategy for the day, in both deterministic and stochastic settings. MIT's cogeneration plant is used as a case study, with other examples throughout the thesis demonstrate the use of TOTEM for assessing and controlling renewable resources, storage options, andby David Craft.Ph.D