57 research outputs found
Introduction to Neuromorphic Computing
Neuromorphic computing is an emerging field that has the potential to drastically influence every human’s life within the next decades. Neuromorphic computing explores the computing process of the brain and attempts to replicate it onto modern electronics. It offers improvements on current computer architecture, the von Neumann architecture, and will lead to more efficient computing, easier development of machine learning, and further integration of electronics and biology
Emulating short-term synaptic dynamics with memristive devices
Neuromorphic architectures offer great promise for achieving computation capacities beyond conventional Von Neumann machines. The essential elements for achieving this vision are highly scalable synaptic mimics that do not undermine biological fidelity. Here we demonstrate that single solid-state TiO2 memristors can exhibit non-associative plasticity phenomena observed in biological synapses, supported by their metastable memory state transition properties. We show that, contrary to conventional uses of solid-state memory, the existence of rate-limiting volatility is a key feature for capturing short-term synaptic dynamics. We also show how the temporal dynamics of our prototypes can be exploited to implement spatio-temporal computation, demonstrating the memristors full potential for building biophysically realistic neural processing systems
Capacitive effects and memristive switching in three terminal multilayered MoS<inf>2</inf>devices
We report on the electrical properties of gated two-terminal multilayered molybdenum disulfide (MoS2) memristor devices having a planar architecture. The approach based on highly dispersed MoS2 flakes drop cast onto a bottom gated Si/SiO2 (100nm) wafer containing metal Pd contact electrodes yields devices that exhibit a number of complex properties including memristive and capacitive effects as well as multiple non-zero-crossing current-voltage hysteresis effects. The devices also show a reaction to a varying gate bias. An increasingly positive gate led to the devices displaying a linear ohmic I-V response while an increasingly negative gate bias drove the system to behave more memristive with a widening hysteresis loop
A CMOS Spiking Neuron for Dense Memristor-Synapse Connectivity for Brain-Inspired Computing
Neuromorphic systems that densely integrate CMOS spiking neurons and
nano-scale memristor synapses open a new avenue of brain-inspired computing.
Existing silicon neurons have molded neural biophysical dynamics but are
incompatible with memristor synapses, or used extra training circuitry thus
eliminating much of the density advantages gained by using memristors, or were
energy inefficient. Here we describe a novel CMOS spiking leaky
integrate-and-fire neuron circuit. Building on a reconfigurable architecture
with a single opamp, the described neuron accommodates a large number of
memristor synapses, and enables online spike timing dependent plasticity (STDP)
learning with optimized power consumption. Simulation results of an 180nm CMOS
design showed 97% power efficiency metric when realizing STDP learning in
10,000 memristor synapses with a nominal 1M{\Omega} memristance, and only
13{\mu}A current consumption when integrating input spikes. Therefore, the
described CMOS neuron contributes a generalized building block for large-scale
brain-inspired neuromorphic systems.Comment: This is a preprint of an article accepted for publication in
International Joint Conference on Neural Networks (IJCNN) 201
A geographically distributed bio-hybrid neural network with memristive plasticity
Throughout evolution the brain has mastered the art of processing real-world
inputs through networks of interlinked spiking neurons. Synapses have emerged
as key elements that, owing to their plasticity, are merging neuron-to-neuron
signalling with memory storage and computation. Electronics has made important
steps in emulating neurons through neuromorphic circuits and synapses with
nanoscale memristors, yet novel applications that interlink them in
heterogeneous bio-inspired and bio-hybrid architectures are just beginning to
materialise. The use of memristive technologies in brain-inspired architectures
for computing or for sensing spiking activity of biological neurons8 are only
recent examples, however interlinking brain and electronic neurons through
plasticity-driven synaptic elements has remained so far in the realm of the
imagination. Here, we demonstrate a bio-hybrid neural network (bNN) where
memristors work as "synaptors" between rat neural circuits and VLSI neurons.
The two fundamental synaptors, from artificial-to-biological (ABsyn) and from
biological-to- artificial (BAsyn), are interconnected over the Internet. The
bNN extends across Europe, collapsing spatial boundaries existing in natural
brain networks and laying the foundations of a new geographically distributed
and evolving architecture: the Internet of Neuro-electronics (IoN).Comment: 16 pages, 10 figure
Unidirectional synapse-like behavior of Zr/ZrO2-NT/Au layered structure
Zirconia nanotubular layer with an outer tube diameter 25 nm was synthesized by potentiostatic anodization. The Zr/ZrO2-NT/Au memristive structure is fabricated using stencil mask and magnetron sputtering techniques. Current-voltage characteristics are measured in full cycles of resistive switching with varying parameters of the applied harmonic voltage. An equivalent circuit with unidirectional electrical conductivity for the studied structure is proposed. Estimates of the electrical resistance of memristors in high-and intermediate resistivity states are performed. The high synaptic plasticity of memristors based on the Zr/ZrO2-NT/Au structure is shown. © 2018 IEEE
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