58 research outputs found
Embracing the Unreliability of Memory Devices for Neuromorphic Computing
The emergence of resistive non-volatile memories opens the way to highly
energy-efficient computation near- or in-memory. However, this type of
computation is not compatible with conventional ECC, and has to deal with
device unreliability. Inspired by the architecture of animal brains, we present
a manufactured differential hybrid CMOS/RRAM memory architecture suitable for
neural network implementation that functions without formal ECC. We also show
that using low-energy but error-prone programming conditions only slightly
reduces network accuracy
Self-Testing Analog Spiking Neuron Circuit
International audienceHardware-implemented neural networks are foreseen to play an increasing role in numerous applications. In this paper, we address the problem of post-manufacturing test and self-test of hardware-implemented neural networks. In particular, we propose a self-testable version of a spiking neuron circuit. The self-test wrapper is a compact circuit composed of a low-precision ramp generator and a small digital block. The self-test principle is demonstrated on a spiking neuron circuit design in 0.35µm CMOS technology
Charge-Trapping-Induced Compensation of the Ferroelectric Polarization in FTJs: Optimal Conditions for a Synaptic Device Operation
In this work, we present a clear evidence, based on numerical simulations and
experiments, that the polarization compensation due to trapped charge strongly
influences the ON/ OFF ratio in Hf 0.5 Zr 0.5 O 2 (HZO)-based ferroelectric
tunnel junctions (FTJs). Furthermore, we identify and explain compensation
conditions that enable an optimal operation of FTJs. Our results provide both
key physical insights and design guidelines for the operation of FTJs as
multilevel synaptic devices
Current localisation and redistribution as the basis of discontinuous current controlled negative differential resistance in NbOx
In-situ thermo-reflectance imaging is used to show that the discontinuous,
snap-back mode of current-controlled negative differential resistance (CC-NDR)
in NbOx-based devices is a direct consequence of current localization and
redistribution. Current localisation is shown to result from the creation of a
conductive filament either during electroforming or from current bifurcation
due to the super-linear temperature dependence of the film conductivity. The
snap-back response then arises from current redistribution between regions of
low and high current-density due to the rapid increase in conductivity created
within the high current density region. This redistribution is further shown to
depend on the relative resistance of the low current-density region with the
characteristics of NbOx cross-point devices transitioning between continuous
and discontinuous snap-back modes at critical values of film conductivity,
area, thickness and temperature, as predicted. These results clearly
demonstrate that snap-back is a generic response that arises from current
localization and redistribution within the oxide film rather than a
material-specific phase transition, thus resolving a long-standing controversy.Comment: 21 Page
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