Recent years have seen rapid strides in the level of sophistication of VLSI circuits. On the performance front, there is a vital need for techniques to design fast, low-power chips with minimum area for increasingly complex systems, while on the economic side there is the vastly increased pressure of time-to-market. These pressures have made the use of CAD tools mandatory in designing complex systems. Timing Analysis and Optimization of Sequential Circuits describes CAD algorithms for analyzing and optimizing the timing behavior of sequential circuits with special reference to performance parameters such as power and area. A unified approach to performance analysis and optimization of sequential circuits is presented. The state of the art in timing analysis and optimization techniques is described for circuits using edge-triggered or level-sensitive memory elements. Specific emphasis is placed on two methods that are true sequential timing optimizations techniques: retiming and clock skew optimization. Timing Analysis and Optimization of Sequential Circuits covers the following topics: Algorithms for sequential timing analysis Fast algorithms for clock skew optimization and their applications Efficient techniques for retiming large sequential circuits Coupling sequential and combinational optimizations. Timing Analysis and Optimization of Sequential Circuits is written for graduate students, researchers and professionals in the area of CAD for VLSI and VLSI circuit design.

History of the Book The last three decades have witnessed an explosive development in integrated circuit fabrication technologies. The complexities of cur rent CMOS circuits are reaching beyond the 100 nanometer feature size and multi-hundred million transistors per integrated circuit. To fully exploit this technological potential, circuit designers use sophisticated Computer-Aided Design (CAD) tools. While supporting the talents of innumerable microelectronics engineers, these CAD tools have become the enabling factor responsible for the successful design and implemen tation of thousands of high performance, large scale integrated circuits. This research monograph originated from a body of doctoral disserta tion research completed by the first author at the University of Rochester from 1994 to 1999 while under the supervision of Prof. Eby G. Friedman. This research focuses on issues in the design of the clock distribution net work in large scale, high performance digital synchronous circuits and particularly, on algorithms for non-zero clock skew scheduling. During the development of this research, it has become clear that incorporating timing issues into the successful integrated circuit design process is of fundamental importance, particularly in that advanced theoretical de velopments in this area have been slow to reach the designers' desktops.

With the advent of nanometer technologies, circuit performance constraints are becoming ever more stringent. In this context, automated timing analysis and optimization becomes imperative for the design of high-performance circuits that must satisfy a demanding set of constraints. Timing overviews the state of the art in timing analysis and optimization, and is intended to serve as a compendium that can provide an introduction to the uninitiated reader, as a ready reference for a practitioner, or as a source for the accomplished researcher. A comprehensive overview of the basics of timing analysis is provided, and this is augmented with techniques that incorporate physical effects arising in deep submicron and nanometer technologies. The book provides an in-depth treatment of the analysis of interconnect systems, static timing analysis for combinational circuits, timing analysis for sequential circuits, and timing optimization techniques at the transistor and layout levels. The intended audience includes CAD tool developers, graduate students, research professionals, and the merely curious.

Every day, companies call upon their signal integrity engineers to make difficult decisions about design constraints and timing margins. Can I move these wires closer together? How many holes can I drill in this net? How far apart can I place these chips? Each design is unique: there’s no single recipe that answers all the questions. Today’s designs require ever greater precision, but design guides for specific digital interfaces are by nature conservative. Now, for the first time, there’s a complete guide to timing analysis and simulation that will help you manage the tradeoffs between signal integrity, performance, and cost. Writing from the perspective of a practicing SI engineer and team lead, Greg Edlund of IBM presents deep knowledge and quantitative techniques for making better decisions about digital interface design. Edlund shares his insights into how and why digital interfaces fail, revealing how fundamental sources of pathological effects can combine to create fault conditions. You won’t just learn Edlund’s expert techniques for avoiding failures: you’ll learn how to develop the right approach for your own projects and environment. Coverage includes • Systematically ensure that interfaces will operate with positive timing margin over the product’s lifetime–without incurring excess cost • Understand essential chip-to-chip timing concepts in the context of signal integrity • Collect the right information upfront, so you can analyze new designs more effectively • Review the circuits that store information in CMOS state machines–and how they fail • Learn how to time common-clock, source synchronous, and high-speed serial transfers • Thoroughly understand how interconnect electrical characteristics affect timing: propagation delay, impedance profile, crosstalk, resonances, and frequency-dependent loss • Model 3D discontinuities using electromagnetic field solvers • Walk through four case studies: coupled differential vias, land grid array connector, DDR2 memory data transfer, and PCI Express channel • Appendices present a refresher on SPICE modeling and a high-level conceptual framework for electromagnetic field behavior Objective, realistic, and practical, this is the signal integrity resource engineers have been searching for. Preface xiii Acknowledgments xvi About the Author xix About the Cover xx Chapter 1: Engineering Reliable Digital Interfaces 1 Chapter 2: Chip-to-Chip Timing 13 Chapter 3: Inside IO Circuits 39 Chapter 4: Modeling 3D Discontinuities 73 Chapter 5: Practical 3D Examples 101 Chapter 6: DDR2 Case Study 133 Chapter 7: PCI Express Case Study 175 Appendix A: A Short CMOS and SPICE Primer 209 Appendix B: A Stroll Through 3D Fields 219 Endnotes 233 Index 235

The continued scaling of digital integrated circuits has led to an increasingly larger impact of process, supply voltage, and temperature (PVT) variations. The effect of these variations on logic cell and interconnect delays has introduced challenges to both circuit performance (timing) verification and optimization. In order for us to fully take advantage of the benefits of technology scaling, it is essential that "variation-aware" techniques for performance verification and optimization be developed and used in modern design flows.In this thesis such techniques for both performance verification and optimization are presented. First, we present a fast method for finding the worst-case slacks over all process and environmental corners. This method uses the standard set of PVT corners available in industry, and provides large runtime gains while maintaining a high degree of accuracy. After that, we propose an efficient block-based parameterized timing analysis technique that can accurately capture circuit delays at every point in the parameter space, by reporting all paths that can become critical. This method employs parameterized static timing analysis (PSTA) variability models, and allows one to easily examine local robustness to parameters in different regions of the parameter space. Next, we introduce an optimization method that alters clock network lines so that a circuit meets its timing constraints at all PVT settings under PSTA variability models. This is formulated as a Linear Program (LP), which is based on a clock skew optimization formulation, and as a result it can be solved efficiently. Finally, we present a method that uses characterized, pre-silicon, PSTA variational timing models to identify speedpaths that can best explain the observed delay measurements during silicon debug. This is a crucial step, required for both "fixing"' failing paths and for accurate learning from silicon data.

This book constitutes the refereed proceedings of the 16th International Workshop on Power and Timing Modeling, Optimization and Simulation, PATMOS 2006. The book presents 41 revised full papers and 23 revised poster papers together with 4 key notes and 3 industrial abstracts. Topical sections include high-level design, power estimation and modeling memory and register files, low-power digital circuits, busses and interconnects, low-power techniques, applications and SoC design, modeling, and more.

The International Workshop on Power and Timing Modeling, Optimization, and Simulation PATMOS 2002, was the 12th in a series of international workshops 1 previously held in several places in Europe. PATMOS has over the years evolved into a well-established and outstanding series of open European events on power and timing aspects of integrated circuit design. The increased interest, espe- ally in low-power design, has added further momentum to the interest in this workshop. Despite its growth, the workshop can still be considered as a very - cused conference, featuring high-level scienti?c presentations together with open discussions in a free and easy environment. This year, the workshop has been opened to both regular papers and poster presentations. The increasing number of worldwide high-quality submissions is a measure of the global interest of the international scienti?c community in the topics covered by PATMOS. The objective of this workshop is to provide a forum to discuss and inves- gate the emerging problems in the design methodologies and CAD-tools for the new generation of IC technologies. A major emphasis of the technical program is on speed and low-power aspects with particular regard to modeling, char- terization, design, and architectures. The technical program of PATMOS 2002 included nine sessions dedicated to most important and current topics on power and timing modeling, optimization, and simulation. The three invited talks try to give a global overview of the issues in low-power and/or high-performance circuit design.

This book constitutes the refereed proceedings of the 13th International Workshop on Power and Timing Modeling, Optimization and Simulation, PATMOS 2003, held in Torino, Italy in September 2003. The 43 revised full papers and 18 revised poster papers presented together with three keynote contributions were carefully reviewed and selected from 85 submissions. The papers are organized in topical sections on gate-level modeling and characterization, interconnect modeling and optimization, asynchronous techniques, RTL power modeling and memory optimization, high-level modeling, power-efficient technologies and designs, communication modeling and design, and low-power issues in processors and multimedia.

Timing research in high performance VLSI systems has advanced at a steady pace over the last few years, while tools, especially theoretical mechanisms, lag behind. Much present timing research relies heavily on timing diagrams, which, although intuitive, are inadequate for analysis of large designs with many parameters. Further, timing diagrams offer only approximations, not exact solutions, to many timing problems and provide little insight in the cases where temporal properties of a design interact intricately with the design's logical functionalities. This book presents a methodology for timing research which facilitates analy sis and design of circuits and systems in a unified temporal and logical domain. In the first part, we introduce an algebraic representation formalism, Timed Boolean Functions (TBF's), which integrates both logical and timing informa tion of digital circuits and systems into a single formalism. We also give a canonical form, TBF BDD's, for them, which can be used for efficient ma nipulation. In the second part, we apply Timed Boolean Functions to three problems in timing research, for which exact solutions are obtained for the first time: 1. computing the exact delays of combinational circuits and the minimum cycle times of finite state machines, 2. analysis and synthesis of wavepipelining circuits, a high speed architecture for which precise timing relations between signals are essential for correct operations, 3. verification of circuit and system performance and coverage of delay faults by testing.