Quantum and spin-based tunneling devices for memory systems

Rapid developments in information technology, such as internet, portable computing, and wireless communication, create a huge demand for fast and reliable ways to store and process information. Thus far, this need has been paralleled with the revolution in solid-state memory technologies. Memory devices, such as SRAM, DRAM, and flash, have been widely used in most electronic products. The primary strategy to keep up the trend is miniaturization. CMOS devices have been scaled down beyond sub-45 nm, the size of only a few atomic layers. Scaling, however, will soon reach the physical limitation of the material and cease to yield the desired enhancement in device performance. In this thesis, an alternative method to scaling is proposed and successfully realized. The proposed scheme integrates quantum devices, Si/SiGe resonant interband tunnel diodes (RITD), with classical CMOS devices forming a microsystem of disparate devices to achieve higher performance as well as higher density. The device/circuit designs, layouts and masks involving 12 levels were fabricated utilizing a process that incorporates nearly a hundred processing steps. Utilizing unique characteristics of each component, a low-power tunneling-based static random access memory (TSRAM) has been demonstrated. The TSRAM cells exhibit bistability operation with a power supply voltage as low as 0.37 V. Various TSRAM cells were also constructed and their latching mechanisms have been extensively investigated. In addition, the operation margins of TSRAM cells are evaluated based on different device structures and temperature variation from room temperature up to 200oC. The versatility of TSRAM is extended beyond the binary system. Using multi-peak Si/SiGe RITD, various multi-valued TSRAM (MV-TSRAM) configurations that can store more than two logic levels per cell are demonstrated. By this virtue, memory density can be substantially increased. Using two novel methods via ambipolar operation and utilization of enable/disable transistors, a six-valued MV-TSRAM cell are demonstrated. A revolutionary novel concept of integrating of Si/SiGe RITD with spin tunnel devices, magnetic tunnel junctions (MTJ), has been developed. This hybrid approach adds non-volatility and multi-valued memory potential as demonstrated by theoretical predictions and simulations. The challenges of physically fabricating these devices have been identified. These include process compatibility and device design. A test bed approach of fabricating RITD-MTJ structures has been developed. In conclusion, this body of work has created a sound foundation for new research frontiers in four different major areas: integrated TSRAM system, MV-TSRAM system, MTJ/RITD-based nonvolatile MRAM, and RITD/CMOS logic circuits

Reduced Footprint Probabilistic Inference Networks Using Novel Hybrid SHE-MTJ/CMOS Based Majority Gate

In recent years, innovations in machine learning using artificial neural networks (ANN) have significantly increased and led to various applications like image recognition, text classification, machine translation, sequence recognition, etc. Earlier, research was focused on software-based DBNs, which are implemented on conventional von-Neumann architectures that provided flexibility but had few limitations. Recent studies have implemented hardware-based designs like FPGA-based, CMOS based, RRAM-based, and MRAM-based designs to overcome these limitations. Hybrid CMOS-MTJ-based RBMs provided significant area and energy improvements compared to other techniques. We herein implemented Spatial and Temporal redundant probabilistic interpolation network to improve the accuracy and provide fault tolerance with the help of a low-power and area-efficient novel SHE-MTJ-based majority gate. Also, Progressive Modular Redundant Network is Proposed to enhance reduced footprint when compared with the Spatial modular Redundant network. Results show that the SHE-MTJ-based majority gate provides 32.1% area reduction and 54.5% energy reduction compared to the conventional CMOS-based design. Also, the simulation results show that the proposed model improved 36% in Error rate, in addition to latency improvements when compared with baseline models. An accuracy comparison of all the redundant models for two different topologies, 784x200x10, and 784x200x200x10, and for different activation functions including Sigmoid, Square root and Square indicate viability of the methods developed with respect to area and energy metrics

Exploration of Nonlinear Devices and Nonlinear Transmission Line Techniques for Microwaves Applications

RÉSUMÉ Les systèmes de communication modernes dépendent fortement des circuits non linéaires, tels que les amplificateurs de puissance (PA), les mélangeurs, les multiplicateurs, les oscillateurs, les commutateurs, etc., qui sont construits à partir de composants non linéaires passifs (comme des diodes) ou actifs (par exemple des transistors). Cette thèse étudie les dispositifs non linéaires passifs traditionnels et émergents, ainsi que les techniques de lignes de transmission non linéaires (NLTL). Plusieurs de leurs applications micro-ondes ont également été étudiées, y compris la récupération d'énergie sans fil, la synthèse d’impédance électronique et l’adaptation d’impédance bidimensionnelle (inductive et capacitive). Dans le chapitre 1, sont d'abord étudiés les dispositifs non linéaires traditionnels résistifs, capacitifs et inductifs. Les dispositifs non linéaires émergents, y compris les dispositifs MEMS et la spindiode, sont ensuite explorés. La construction physique de base, les principes de fonctionnement, ainsi que les caractéristiques et applications pour divers types de dispositifs non linéaires sont expliqués et comparés. Les lignes de transmission non-linéaires (NLTL) traditionnelles utilisant des dispositifs non linéaires capacitifs (varactor, BST etc.) ou inductifs (ferrite saturée), et la technique hybride NLTL émergente utilisant à la fois des dispositifs non linéaires capacitifs et inductifs sont également étudiées. Le chapitre 2 examine les techniques de conversion d'énergie micro-ondes à courant-continu de faible puissance à la fine pointe de la technologie. Une image complète de l'état de l'art sur cet aspect est donnée graphiquement. Elle compare différentes technologies telles que le transistor, la diode et les technologies CMOS. Depuis le tout début des techniques intégrées RF et micro-ondes et de la récupération d'énergie, les diodes Schottky ont été le plus souvent utilisées dans les circuits de mélange et de redressement. Cependant, dans des applications spécifiques de récupération d'énergie, la technique des diodes Schottky ne parvient pas à fournir une efficacité satisfaisante de conversion RF-dc. Suite aux limitations mises en évidence des dispositifs actuels, ce travail introduit, pour la première fois, un composant non linéaire pour une redressement de faible puissance, basé sur une découverte récente en spintronique, à savoir, la jonction tunnel magnétique, parfois appelée spindiode. Un modèle équivalent de spindiode est développé pour décrire le comportement en fréquence.----------ABSTRACT Modern communication systems are heavily dependent on nonlinear circuits, such as PA, mixer, multiplier, oscillator, switch, etc., the core of which are either passive nonlinear elements and devices (e.g. diodes) or active nonlinear components and devices (e.g. transistors). This thesis aims at investigating a number of traditional and emerging passive nonlinear devices and nonlinear transmission line (NLTL) techniques, and developing four of their microwave applications such as wireless power harvesting, electronic impedance synthesizer, and two-dimensional tuning circuit. In Chapter 1, traditional nonlinear devices in terms of the categories of resistive, capacitive and inductive are firstly investigated. Emerging nonlinear devices including microelectromechanical system (MEMS) devices and spindiodes are then explored. The basic physical constructions, operation principles, and characteristics as well as applications of various types of nonlinear devices are explained and compared. Traditional NLTL techniques make use of either capacitive nonlinear devices (varactor, BST etc.) or inductive nonlinear devices (saturated ferrite), and emerging hybrid NLTL techniques are also studied through the deployment of both nonlinear capacitive and inductive devices. Chapter 2 examines the state-of-the-art low-power microwave-to-dc energy conversion techniques. A comprehensive picture of the state-of-the-art on this aspect is given graphically, which compares different technologies such as transistor, diode, and CMOS schemes. Since the very beginning of RF and microwave integrated techniques and energy harvesting, Schottky diodes as the undisputable dominant choice, have been widely used in mixing and rectifying circuits. However, in specific μW power-harvesting applications, the Schottky diode technique seemingly fails to provide a satisfactory RF–dc conversion. Subsequent to the highlighted limitations of current devices, this work introduces, for the first time, a nonlinear component for low-power rectification based on a recent discovery in spintronics, namely, the Magnetic Tunnel Junction, also called spindiode. An equivalent model of spindiode is developed to describe the frequency behavior. Full parametric studies show that the interfacial capacitance, rather than the geometric capacitance, as it is usually the case for diode, plays a crucial role in the drop of efficiency in microwave frequency applications

Intelligent Circuits and Systems

ICICS-2020 is the third conference initiated by the School of Electronics and Electrical Engineering at Lovely Professional University that explored recent innovations of researchers working for the development of smart and green technologies in the fields of Energy, Electronics, Communications, Computers, and Control. ICICS provides innovators to identify new opportunities for the social and economic benefits of society.　 This conference bridges the gap between academics and R&D institutions, social visionaries, and experts from all strata of society to present their ongoing research activities and foster research relations between them. It provides opportunities for the exchange of new ideas, applications, and experiences in the field of smart technologies and finding global partners for future collaboration. The ICICS-2020 was conducted in two broad categories, Intelligent Circuits & Intelligent Systems and Emerging Technologies in Electrical Engineering