William J. Dally

Digital Systems Engineering: Acknowledgment

What makes some computers slow? What makes some digital systems operate reliably for years while others fail mysteriously every few hours? Why do some systems dissipate kilowatts while others operate off batteries? These questions of speed, reliability, and power are all determined by the system-level electrical design of a digital system. Digital Systems Engineering presents a comprehensive treatment of these topics. It combines a rigorous development of the fundamental principles in each area with down-to-earth examples of circuits and methods that work in practice. The book not only can serve as an undergraduate textbook, filling the gap between circuit design and logic design, but also can help practicing digital designers keep up with the speed and power of modern integrated circuits. The techniques described in this book, which were once used only in supercomputers, are now essential to the correct and efficient operation of any type of digital system.

Digital Systems Engineering: Frontmatter

What makes some computers slow? What makes some digital systems operate reliably for years while others fail mysteriously every few hours? Why do some systems dissipate kilowatts while others operate off batteries? These questions of speed, reliability, and power are all determined by the system-level electrical design of a digital system. Digital Systems Engineering presents a comprehensive treatment of these topics. It combines a rigorous development of the fundamental principles in each area with down-to-earth examples of circuits and methods that work in practice. The book not only can serve as an undergraduate textbook, filling the gap between circuit design and logic design, but also can help practicing digital designers keep up with the speed and power of modern integrated circuits. The techniques described in this book, which were once used only in supercomputers, are now essential to the correct and efficient operation of any type of digital system.

A 28 nm 2 Mbit 6 T SRAM With Highly Configurable Low-Voltage Write-Ability Assist Implementation and Capacitor-Based Sense-Amplifier Input Offset Compensation

This paper presents a highly configurable low-voltage write-ability assist implementation along with a sense-amplifier offset reduction technique to improve SRAM read performance. Write-assist implementation combines negative bit-line (BL) and VDD collapse schemes in an efficient way to maximize Vmin improvements while saving on area and energy overhead of these assists. Relative delay and pulse width of assist control signals are also designed with configurability to provide tuning of assist strengths. Sense-amplifier offset compensation scheme uses capacitors to store and negate threshold mismatch of input transistors. A test chip fabricated in 28 nm TIP CMOS process demonstrates operation down to 0.5 V with write assists and more than 10% reduction in word-line pulsewidth with the offset compensated sense amplifiers.

Digital Systems Engineering: INTRODUCTION TO DIGITAL SYSTEMS ENGINEERING

Digital systems are pervasive in modern society. We use computers for bookkeeping, engineering, publishing, and entertainment. Digital communications systems handle our telephone calls and enable our Web browsing sessions. Other uses of digital systems are less visible. Most consumer electronics products are largely digital and becoming more so. Music today is distributed digitally on compact optical disks, and video production is rapidly becoming a digital process. A typical appliance is controlled digitally by a microcomputer. As many as ten microcomputers can be found in the average car for controlling functions ranging from the sound system to the antilock brakes. A digital system represents information with discrete symbols (of which digits are a special case) rather than with a continuously varying quantity, as in an analog system. Most systems use just two symbols, often denoted by the binary digits (or bits ) 0 and 1, to represent all information. Simple truth propositions are represented directly with a single bit, whereas strings of bits are used to represent more complex data. In a digital system, noise below a given level can be completely rejected. Symbols are encoded into ranges of voltage or current level. If we add a small amount of voltage, V N , to the nominal voltage for the 0 symbol, V 0 , the resulting voltage, V 0 + V N , will still be in the range for a 0 symbol and, more importantly, can be restored to the nominal level, V 0 . This property allows us to process information through many noisy stages of logic with no accumulation of noise.