Energy Efficient and Error Resilient Neuromorphic Computing in VLSI

Energy Efficient and Error Resilient Neuromorphic Computing in VLSI
Author: Yongtae Kim
Publisher:
Total Pages:
Release: 2014
Genre:
ISBN:

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Realization of the conventional Von Neumann architecture faces increasing challenges due to growing process variations, device reliability and power consumption. As an appealing architectural solution, brain-inspired neuromorphic computing has drawn a great deal of research interest due to its potential improved scalability and power efficiency, and better suitability in processing complex tasks. Moreover, inherit error resilience in neuromorphic computing allows remarkable power and energy savings by exploiting approximate computing. This dissertation focuses on a scalable and energy efficient neurocomputing architecture which leverages emerging memristor nanodevices and a novel approximate arithmetic for cognitive computing. First, brain-inspired digital neuromorphic processor (DNP) architecture with memristive synaptic crossbar is presented for large scale spiking neural networks. We leverage memristor nanodevices to build an N x N crossbar array to store not only multibit synaptic weight values but also the network configuration data with significantly reduced area cost. Additionally, the crossbar array is accessible both column- and row-wise to significantly expedite the synaptic weight update process for on-chip learning. The proposed digital pulse width modulator (PWM) readily creates a binary pulse with various durations to read and write the multilevel memristors with low cost. Our design integrates N digital leaky integrate-and-fire (LIF) silicon neurons to mimic their biological counterparts and the respective on-chip learning circuits for implementing spike timing dependent plasticity (STDP) learning rules. The proposed column based analog-to-digital conversion (ADC) scheme accumulates the pre-synaptic weights of a neuron efficiently and reduces silicon area by using only one shared arithmetic unit for processing LIF operations of all N neurons. With 256 silicon neurons, the learning circuits and 64K synapses, the power dissipation and area of our design are evaluated as 6.45 mW and 1.86 mm2, respectively, in a 90 nm CMOS technology. Furthermore, arithmetic computations contribute significantly to the overall processing time and power of the proposed architecture. In particular, addition and comparison operations represent 88.5% and 42.9% of processing time and power for digital LIF computation, respectively. Hence, by exploiting the built-in resilience of the presented neuromorphic architecture, we propose novel approximate adder and comparator designs to significantly reduce energy consumption with a very low error rate. The significantly improved error rate and critical path delay stem from a novel carry prediction technique that leverages the information from less significant input bits in a parallel manner. An error magnitude reduction scheme is proposed to further reduce amount of error once detected with low cost in the proposed adder design. Implemented in a commercial 90 nm CMOS process, it is shown that the proposed adder is up to 2.4x faster and 43% more energy efficient over traditional adders while having an error rate of only 0.18%. Additionally, the proposed comparator achieves an error rate of less than 0.1% and an energy reduction of up to 4.9x compared to the conventional ones. The proposed arithmetic has been adopted in a VLSI-based neuromorphic character recognition chip using unsupervised learning. The approximation errors of the proposed arithmetic units have been shown to have negligible impacts on the training process. Moreover, the energy saving of up to 66.5% over traditional arithmetic units is achieved for the neuromorphic chip with scaled supply levels. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151721

Proceedings of the International Conference on Paradigms of Computing, Communication and Data Sciences

Proceedings of the International Conference on Paradigms of Computing, Communication and Data Sciences
Author: Rajendra Prasad Yadav
Publisher: Springer Nature
Total Pages: 765
Release: 2023-02-23
Genre: Technology & Engineering
ISBN: 9811987424

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This book gathers selected high-quality research papers presented at International Conference on Paradigms of Communication, Computing and Data Sciences (PCCDS 2022), held at Malaviya National Institute of Technology Jaipur, India, during 05 – 07 July 2022. It discusses high-quality and cutting-edge research in the areas of advanced computing, communications and data science techniques. The book is a collection of latest research articles in computation algorithm, communication and data sciences, intertwined with each other for efficiency.

Approximate Circuits

Approximate Circuits
Author: Sherief Reda
Publisher: Springer
Total Pages: 479
Release: 2018-12-05
Genre: Technology & Engineering
ISBN: 3319993224

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This book provides readers with a comprehensive, state-of-the-art overview of approximate computing, enabling the design trade-off of accuracy for achieving better power/performance efficiencies, through the simplification of underlying computing resources. The authors describe in detail various efforts to generate approximate hardware systems, while still providing an overview of support techniques at other computing layers. The book is organized by techniques for various hardware components, from basic building blocks to general circuits and systems.

Machine Learning in VLSI Computer-Aided Design

Machine Learning in VLSI Computer-Aided Design
Author: Ibrahim (Abe) M. Elfadel
Publisher: Springer
Total Pages: 694
Release: 2019-03-15
Genre: Technology & Engineering
ISBN: 3030046664

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This book provides readers with an up-to-date account of the use of machine learning frameworks, methodologies, algorithms and techniques in the context of computer-aided design (CAD) for very-large-scale integrated circuits (VLSI). Coverage includes the various machine learning methods used in lithography, physical design, yield prediction, post-silicon performance analysis, reliability and failure analysis, power and thermal analysis, analog design, logic synthesis, verification, and neuromorphic design. Provides up-to-date information on machine learning in VLSI CAD for device modeling, layout verifications, yield prediction, post-silicon validation, and reliability; Discusses the use of machine learning techniques in the context of analog and digital synthesis; Demonstrates how to formulate VLSI CAD objectives as machine learning problems and provides a comprehensive treatment of their efficient solutions; Discusses the tradeoff between the cost of collecting data and prediction accuracy and provides a methodology for using prior data to reduce cost of data collection in the design, testing and validation of both analog and digital VLSI designs. From the Foreword As the semiconductor industry embraces the rising swell of cognitive systems and edge intelligence, this book could serve as a harbinger and example of the osmosis that will exist between our cognitive structures and methods, on the one hand, and the hardware architectures and technologies that will support them, on the other....As we transition from the computing era to the cognitive one, it behooves us to remember the success story of VLSI CAD and to earnestly seek the help of the invisible hand so that our future cognitive systems are used to design more powerful cognitive systems. This book is very much aligned with this on-going transition from computing to cognition, and it is with deep pleasure that I recommend it to all those who are actively engaged in this exciting transformation. Dr. Ruchir Puri, IBM Fellow, IBM Watson CTO & Chief Architect, IBM T. J. Watson Research Center

Approximate Computing Techniques

Approximate Computing Techniques
Author: Alberto Bosio
Publisher: Springer Nature
Total Pages: 541
Release: 2022-06-10
Genre: Technology & Engineering
ISBN: 303094705X

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This book serves as a single-source reference to the latest advances in Approximate Computing (AxC), a promising technique for increasing performance or reducing the cost and power consumption of a computing system. The authors discuss the different AxC design and validation techniques, and their integration. They also describe real AxC applications, spanning from mobile to high performance computing and also safety-critical applications.

Approximate Computing

Approximate Computing
Author: Weiqiang Liu
Publisher: Springer Nature
Total Pages: 607
Release: 2022-08-22
Genre: Technology & Engineering
ISBN: 3030983471

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This book explores the technological developments at various levels of abstraction, of the new paradigm of approximate computing. The authors describe in a single-source the state-of-the-art, covering the entire spectrum of research activities in approximate computing, bridging device, circuit, architecture, and system levels. Content includes tutorials, reviews and surveys of current theoretical/experimental results, design methodologies and applications developed in approximate computing for a wide scope of readership and specialists. Serves as a single-source reference to state-of-the-art of approximate computing; Covers broad range of topics, from circuits to applications; Includes contributions by leading researchers, from academia and industry.

Intelligent Computing in Engineering

Intelligent Computing in Engineering
Author: Vijender Kumar Solanki
Publisher: Springer Nature
Total Pages: 1159
Release: 2020-04-09
Genre: Technology & Engineering
ISBN: 9811527806

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This book comprises select papers from the international conference on Research in Intelligent and Computing in Engineering (RICE 2019) held at Hanoi University of Industry, Hanoi, Vietnam. The volume focuses on current research on various computing models such as centralized, distributed, cluster, grid and cloud. The contents cover recent advances in wireless sensor networks, mobile ad hoc networks, internet of things, machine learning, grid and cloud computing, and their various applications. The book will help researchers as well as professionals to gain insight into the rapidly evolving fields of internet computing and data mining.

Advances in Smart System Technologies

Advances in Smart System Technologies
Author: P. Suresh
Publisher: Springer Nature
Total Pages: 836
Release: 2020-08-29
Genre: Technology & Engineering
ISBN: 9811550298

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This book presents select peer-reviewed proceedings of the International Conference on Frontiers in Smart Systems Technologies (ICFSST 2019). It focuses on latest research and cutting-edge technologies in smart systems and intelligent autonomous systems with advanced functionality. Comprising topics related to diverse aspects of smart technologies such as high security, reliability, miniaturization, energy consumption, and intelligent data processing, the book contains contributions from academics as well as industry. Given the range of the topics covered, this book will prove useful for students, researchers, and professionals alike.

Cyber-Physical Systems Security

Cyber-Physical Systems Security
Author: Çetin Kaya Koç
Publisher: Springer
Total Pages: 344
Release: 2018-12-06
Genre: Computers
ISBN: 3319989359

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The chapters in this book present the work of researchers, scientists, engineers, and teachers engaged with developing unified foundations, principles, and technologies for cyber-physical security. They adopt a multidisciplinary approach to solving related problems in next-generation systems, representing views from academia, government bodies, and industrial partners, and their contributions discuss current work on modeling, analyzing, and understanding cyber-physical systems.

Appropriateness of Imperfect CNFET Based Circuits for Error Resilient Computing Systems

Appropriateness of Imperfect CNFET Based Circuits for Error Resilient Computing Systems
Author: Kaship Sheikh
Publisher:
Total Pages:
Release: 2020
Genre:
ISBN:

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With superior device performance consistently reported in extremely scaled dimensions, low dimensional materials (LDMs), including Carbon Nanotube Field Effect Transistor (CNFET) based technology, have shown the potential to outperform silicon for future transistors in advanced technology nodes. Studies have also demonstrated orders of magnitude improvement in energy efficiency possible with LDMs, in comparison to silicon at competing technology nodes. However, the current fabrication processes for these materials suffer from process imperfections and still appear to be inadequate to compete with silicon for the mainstream high volume manufacturing. Among the LDMs, CNFETs are the most widely studied and closest to high volume manufacturing. Recent works have shown a significant increase in the complexity of CNFET based systems, including demonstration of a 16-bit microprocessor. However, the design of such systems has involved significantly wider-than-usual transistors and avoidance of certain logic combinations. The resulting complexity of several thousand transistors in such systems is still far from the requirements of high-performance general-purpose computing systems having billions of transistors. With the current progress of the process to fabricate CNFETs, their introduction in mainstream manufacturing is expected to take several more years. For an earlier technology adoption, CNFETs appear to be suited for error-resilient computing systems where errors during computation can be tolerated to a certain degree. Such systems relax the need for precise circuits and a perfect process while leveraging the potential energy benefits of CNFET technology in comparison to conventional Si technology. In this thesis, we explore the potential applications using an imperfect CNFET process for error-resilient computing systems, including the impact of the process imperfections at the system level and methods to improve it. The current most widely adopted fabrication process for CNFETs (separation and placement of solution-based CNTs) still suffers from process imperfections, mainly from open CNTs due to missing of CNTs (in trenches connecting source and drain of CNFET). A fair evaluation of the performance of CNFET based circuits should thus take into consideration the effect of open CNTs, resulting in reduced drive currents. At the circuit level, this leads to failures in meeting 1) the minimum frequency requirement (due to an increase in critical path delay), and 2) the noise suppression requirement. We present a methodology to accurately capture the effect of open CNT imperfection in the state-of-the-art CNFET model, for circuit-level performance evaluation (both delay and glitch vulnerability) of CNFET based circuits using SPICE. A Monte Carlo simulation framework is also provided to investigate the statistical effect of open CNT imperfection on circuit-level performance. We introduce essential metrics to evaluate glitch vulnerability and also provide an effective link between glitch vulnerability and circuit topology. The past few years have observed significant growth of interest in approximate computing for a wide range of applications, including signal processing, data mining, machine learning, image, video processing, etc. In such applications, the result quality is not compromised appreciably, even in the presence of few errors during computation. The ability to tolerate few errors during computation relaxes the need to have precise circuits. Thus the approximate circuits can be designed, with lesser nodes, reduced stages, and reduced capacitance at few nodes. Consequently, the approximate circuits could reduce critical path delays and enhanced noise suppression in comparison to precise circuits. We present a systematic methodology utilizing Reduced Ordered Binary Decision Diagrams (ROBDD) for generating approximate circuits by taking an example of 16-bit parallel prefix CNFET adder. The approximate adder generated using the proposed algorithm has ~ 5x reduction in the average number of nodes failing glitch criteria (along paths to primary output) and 43.4% lesser Energy Delay Product (EDP) even at high open CNT imperfection, in comparison to the ideal case of no open CNT imperfection, at a mean relative error of 3.3%. The recent boom of deep learning has been made possible by VLSI technology advancement resulting in hardware systems, which can support deep learning algorithms. These hardware systems intend to satisfy the high-energy efficiency requirement of such algorithms. The hardware supporting such algorithms adopts neuromorphic-computing architectures with significantly less energy compared to traditional Von Neumann architectures. Deep Neural Networks (DNNs) belonging to deep learning domain find its use in a wide range of applications such as image classification, speech recognition, etc. Recent hardware systems have demonstrated the implementation of complex neural networks at significantly less power. However, the complexity of applications and depths of DNNs are expected to drastically increase in the future, imposing a demanding requirement in terms of scalability and energy efficiency of hardware technology. CNFET technology can be an excellent alternative to meet the aggressive energy efficiency requirement for future DNNs. However, degradation in circuit-level performance due to open CNT imperfection can result in timing failure, thus distorting the shape of non-linear activation function, leading to a significant degradation in classification accuracy. We present a framework to obtain sigmoid activation function considering the effect of open CNT imperfection. A digital neuron is explored to generate the sigmoid activation function, which deviates from the ideal case under imperfect process and reduced time period (increased clock frequency). The inherent error resilience of DNNs, on the other hand, can be utilized to mitigate the impact of imperfect process and maintain the shape of the activation function. We use pruning of synaptic weights, which, combined with the proposed approximate neuron, significantly reduces the chance of timing failures and helps to maintain the activation function shape even at high process imperfection and higher clock frequencies. We also provide a framework to obtain classification accuracy of Deep Belief Networks (class of DNNs based on unsupervised learning) using the activation functions obtained from SPICE simulations. By using both approximate neurons and pruning of synaptic weights, we achieve excellent system accuracy (only