68 research outputs found
Everything You Wish to Know About Memristors But Are Afraid to Ask
This paper classifies all memristors into three classes called Ideal, Generic, or Extended memristors. A subclass of Generic memristors is related to Ideal memristors via a one-to-one mathematical transformation, and is hence called Ideal Generic memristors. The concept of non-volatile memories is defined and clarified with illustrations. Several fundamental new concepts, including Continuum-memory memristor, POP (acronym for Power-Off Plot), DC V-I Plot, and Quasi DC V-I Plot, are rigorously defined and clarified with colorful illustrations. Among many colorful pictures the shoelace DC V-I Plot stands out as both stunning and illustrative. Even more impressive is that this bizarre shoelace plot has an exact analytical representation via 2 explicit functions of the state variable, derived by a novel parametric approach invented by the author
The Fourth Element: Characteristics, Modelling, and Electromagnetic Theory of the Memristor
In 2008, researchers at HP Labs published a paper in {\it Nature} reporting
the realisation of a new basic circuit element that completes the missing link
between charge and flux-linkage, which was postulated by Leon Chua in 1971. The
HP memristor is based on a nanometer scale TiO thin-film, containing a
doped region and an undoped region. Further to proposed applications of
memristors in artificial biological systems and nonvolatile RAM (NVRAM), they
also enable reconfigurable nanoelectronics. Moreover, memristors provide new
paradigms in application specific integrated circuits (ASICs) and field
programmable gate arrays (FPGAs). A significant reduction in area with an
unprecedented memory capacity and device density are the potential advantages
of memristors for Integrated Circuits (ICs). This work reviews the memristor
and provides mathematical and SPICE models for memristors. Insight into the
memristor device is given via recalling the quasi-static expansion of Maxwell's
equations. We also review Chua's arguments based on electromagnetic theory.Comment: 28 pages, 14 figures, Accepted as a regular paper - the Proceedings
of Royal Society
Circuit elements with memory: memristors, memcapacitors and meminductors
We extend the notion of memristive systems to capacitive and inductive
elements, namely capacitors and inductors whose properties depend on the state
and history of the system. All these elements show pinched hysteretic loops in
the two constitutive variables that define them: current-voltage for the
memristor, charge-voltage for the memcapacitor, and current-flux for the
meminductor. We argue that these devices are common at the nanoscale where the
dynamical properties of electrons and ions are likely to depend on the history
of the system, at least within certain time scales. These elements and their
combination in circuits open up new functionalities in electronics and they are
likely to find applications in neuromorphic devices to simulate learning,
adaptive and spontaneous behavior
Reliable SPICE Simulations of Memristors, Memcapacitors and Meminductors
Memory circuit elements, namely memristive, memcapacitive and meminductive systems, are gaining considerable attention due to their ubiquity and use in diverse areas of science and technology. Their modeling within the most widely used environment, SPICE, is thus critical to make substantial progress in the design and analysis of complex circuits. Here, we present a collection of models of different memory circuit elements and provide a methodology for their accurate and reliable modeling in the SPICE environment. We also provide codes of these models written in the most popular SPICE versions (PSpice, LTspice, HSPICE) for the benefit of the reader. We expect this to be of great value to the growing community of scientists interested in the wide range of applications of memory circuit elements
Memcapacitors
Mestrado em Engenharia Eletrónica e TelecomunicaçõesThe present work aims to continue the study of memory devices, initiated with
the prediction of the existence of memristors by Leon Chua in 1971, with the
study and characterization of memcapacitors as a semiconductor two-terminal
device, characterized by the non-linear relation between charge and voltage,
which also present the ability to remember the voltage or charge that passes
through the device, graphically represented by a graphic with hysteresis
characteristics, also presenting a variable capacitance in function of the charge
applied in its terminals.
Here, a characterizationof the response functions to a sinusoidal periodic input
with variable frequency to three mathematical models of memcapacitive
systems is performed: given a memcapacitor in series with an ac input voltage
source, the respective hysteresis charge-voltage plots are studied by
simulations in the MATLAB environment.
Next, a classification of the hysteresis plots in function of its geometry is
performed, given that the crossing of such graph in the (0.0) point defines it as
a type I or type II hysteresis loop.
The analysis continues with the morphological identification of the area of the
hysteresis curve of the first model, by varying amplitude and frequency of the
input source, in such a way to compare the other models with the ideal one, as
well as to take the critical frequencis from which the memcapacitance becomes
constant, and thus the system becomes linear, by making the hysteresis curve
to become a straight line.
The area of the first model was taken by calculations with the Green theorem.O presente trabalho propõe-se a continuar o estudo dos dispositivos de
memória, iniciado com a predição dos memristors por Leon Chua em 1971, por
meio do estudo e caracterização dos memcapacitores como dispositivos
semicondutores de dois terminais, caracterizados pela relação não linear entre
carga e tensão, que apresentam capacidade de recordar a tensão ou corrente
que passa pelo dispositivo, graficamente representado em forma de um gráfico
com características de histerese, aprensentando também capacitância variável
em função da carga aplicada em seus terminais.
Aqui, uma caracterização das funções de resposta a uma entrada periódica
sinusoidal com frequência variável, para três modelos matemáticos de
sistemas memcapacitivos, é realizada: dado um memcapacitor em série com
uma tensão de entrada ac, estuda-se as respectivas funções de histerese
carga-tensão por meio de simulação em MATLAB.
Em seguida, é realizada uma classificação das curvas de histerese em função
da sua geometria, em que a passagem do gráfico no ponto (0,0), de origem
dos planos, o define como tipo I ou tipo II.
A análise prossegue com a identificação morfológica da área das curvas de
histerese obtidas dos primeiro modelo teóricos em causa, variando-se, para
isso, amplitude e frequência de entradas, de modo a se comparar os outros
dois modelos restantes com este modelo ideal, ao mesmo tempo em que se
deseja obter as frequências críticas de cada modelo, ou seja, as frequências e
amplitudes a partir das quais a memcapacitância torna-se constante, e o
sistema em causa, linear, fazendo então a curva de histerese degenerar para
uma reta.
A área do primeiro modelo foi calculada através de um algoritmo que calcula a
área da curva por meio do Teorema de Green
Memristor Platforms for Pattern Recognition Memristor Theory, Systems and Applications
In the last decade a large scientific community has focused on the study of the
memristor. The memristor is thought to be by many the best alternative to CMOS
technology, which is gradually showing its flaws. Transistor technology has developed
fast both under a research and an industrial point of view, reducing the
size of its elements to the nano-scale. It has been possible to generate more and
more complex machinery and to communicate with that same machinery thanks
to the development of programming languages based on combinations of boolean
operands. Alas as shown by Moore’s law, the steep curve of implementation and
of development of CMOS is gradually reaching a plateau. It is clear the need of
studying new elements that can combine the efficiency of transistors and at the same
time increase the complexity of the operations.
Memristors can be described as non-linear resistors capable of maintaining
memory of the resistance state that they reached. From their first theoretical treatment
by Professor Leon O. Chua in 1971, different research groups have devoted their
expertise in studying the both the fabrication and the implementation of this new
promising technology. In the following thesis a complete study on memristors
and memristive elements is presented. The road map that characterizes this study
departs from a deep understanding of the physics that govern memristors, focusing
on the HP model by Dr. Stanley Williams. Other devices such as phase change
memories (PCMs) and memristive biosensors made with Si nano-wires have been
studied, developing emulators and equivalent circuitry, in order to describe their
complex dynamics. This part sets the first milestone of a pathway that passes trough
more complex implementations such as neuromorphic systems and neural networks
based on memristors proving their computing efficiency. Finally it will be presented
a memristror-based technology, covered by patent, demonstrating its efficacy for
clinical applications. The presented system has been designed for detecting and
assessing automatically chronic wounds, a syndrome that affects roughly 2% of
the world population, through a Cellular Automaton which analyzes and processes
digital images of ulcers. Thanks to its precision in measuring the lesions the proposed
solution promises not only to increase healing rates, but also to prevent the worsening
of the wounds that usually lead to amputation and death
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