Robust Design of Variation-sensitive Digital Circuits

Robust Design of Variation-sensitive Digital Circuits
Title Robust Design of Variation-sensitive Digital Circuits PDF eBook
Author Hassan Mostafa
Publisher
Pages 226
Release 2011
Genre
ISBN

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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.

Robust Design of Digital Circuits on Foil

Robust Design of Digital Circuits on Foil
Title Robust Design of Digital Circuits on Foil PDF eBook
Author Kris Myny
Publisher Cambridge University Press
Pages 181
Release 2016-09-22
Genre Technology & Engineering
ISBN 1316654206

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Covering both TFT technologies, and the theory and practice of circuit design, this book equips engineers with the technical knowledge and hands-on skills needed to make circuits on foil with organic or metal oxide based TFTs for applications such as flexible displays and RFID. It provides readers with a solid theoretical background and gives an overview of current TFT technologies including device architecture, typical parameters, and a theoretical framework for comparing different logical families. Concrete, real-world design cases, such as RFID circuits, and organic and metal oxide TFT-based 8-bit microprocessors, enable readers to grasp the practical potential of these design techniques and how they can be applied. This is an essential guide for students and professionals who need to make better transistors on foil.

Ultra-Low-Voltage Design of Energy-Efficient Digital Circuits

Ultra-Low-Voltage Design of Energy-Efficient Digital Circuits
Title Ultra-Low-Voltage Design of Energy-Efficient Digital Circuits PDF eBook
Author Nele Reynders
Publisher Springer
Pages 207
Release 2015-04-14
Genre Technology & Engineering
ISBN 3319161369

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This book focuses on increasing the energy-efficiency of electronic devices so that portable applications can have a longer stand-alone time on the same battery. The authors explain the energy-efficiency benefits that ultra-low-voltage circuits provide and provide answers to tackle the challenges which ultra-low-voltage operation poses. An innovative design methodology is presented, verified, and validated by four prototypes in advanced CMOS technologies. These prototypes are shown to achieve high energy-efficiency through their successful functionality at ultra-low supply voltages.

Statistical Robust Design

Statistical Robust Design
Title Statistical Robust Design PDF eBook
Author Magnus Arner
Publisher John Wiley & Sons
Pages 259
Release 2014-04-28
Genre Mathematics
ISBN 111862503X

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A UNIQUELY PRACTICAL APPROACH TO ROBUST DESIGN FROM A STATISTICAL AND ENGINEERING PERSPECTIVE Variation in environment, usage conditions, and the manufacturing process has long presented a challenge in product engineering, and reducing variation is universally recognized as a key to improving reliability and productivity. One key and cost-effective way to achieve this is by robust design – making the product as insensitive as possible to variation. With Design for Six Sigma training programs primarily in mind, the author of this book offers practical examples that will help to guide product engineers through every stage of experimental design: formulating problems, planning experiments, and analysing data. He discusses both physical and virtual techniques, and includes numerous exercises and solutions that make the book an ideal resource for teaching or self-study. • Presents a practical approach to robust design through design of experiments. • Offers a balance between statistical and industrial aspects of robust design. • Includes practical exercises, making the book useful for teaching. • Covers both physical and virtual approaches to robust design. • Supported by an accompanying website (www.wiley/com/go/robust) featuring MATLAB® scripts and solutions to exercises. • Written by an experienced industrial design practitioner. This book’s state of the art perspective will be of benefit to practitioners of robust design in industry, consultants providing training in Design for Six Sigma, and quality engineers. It will also be a valuable resource for specialized university courses in statistics or quality engineering.

Robust Design of Digital Circuits on Foil

Robust Design of Digital Circuits on Foil
Title Robust Design of Digital Circuits on Foil PDF eBook
Author Kris Myny
Publisher Cambridge University Press
Pages 181
Release 2016-09-22
Genre Computers
ISBN 1107127017

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A practical guide to the theory and applications of TFT technologies and circuit designs for those in academia and in industry.

RF-Frontend Design for Process-Variation-Tolerant Receivers

RF-Frontend Design for Process-Variation-Tolerant Receivers
Title RF-Frontend Design for Process-Variation-Tolerant Receivers PDF eBook
Author Pooyan Sakian
Publisher Springer Science & Business Media
Pages 181
Release 2012-02-18
Genre Technology & Engineering
ISBN 1461421217

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This book discusses wireless receiver design challenges, given the shrinking of circuitry into ever-smaller sizes and resulting complications on manufacturability, production yield and end price of the products. Includes countermeasures for RF designers.

Essentials of Electronic Testing for Digital, Memory and Mixed-Signal VLSI Circuits

Essentials of Electronic Testing for Digital, Memory and Mixed-Signal VLSI Circuits
Title Essentials of Electronic Testing for Digital, Memory and Mixed-Signal VLSI Circuits PDF eBook
Author M. Bushnell
Publisher Springer Science & Business Media
Pages 690
Release 2006-04-11
Genre Technology & Engineering
ISBN 0306470403

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The modern electronic testing has a forty year history. Test professionals hold some fairly large conferences and numerous workshops, have a journal, and there are over one hundred books on testing. Still, a full course on testing is offered only at a few universities, mostly by professors who have a research interest in this area. Apparently, most professors would not have taken a course on electronic testing when they were students. Other than the computer engineering curriculum being too crowded, the major reason cited for the absence of a course on electronic testing is the lack of a suitable textbook. For VLSI the foundation was provided by semiconductor device techn- ogy, circuit design, and electronic testing. In a computer engineering curriculum, therefore, it is necessary that foundations should be taught before applications. The field of VLSI has expanded to systems-on-a-chip, which include digital, memory, and mixed-signalsubsystems. To our knowledge this is the first textbook to cover all three types of electronic circuits. We have written this textbook for an undergraduate “foundations” course on electronic testing. Obviously, it is too voluminous for a one-semester course and a teacher will have to select from the topics. We did not restrict such freedom because the selection may depend upon the individual expertise and interests. Besides, there is merit in having a larger book that will retain its usefulness for the owner even after the completion of the course. With equal tenacity, we address the needs of three other groups of readers.