22,710 research outputs found
Computational paradigm for dynamic logic-gates in neuronal activity
In 1943 McCulloch and Pitts suggested that the brain is composed of reliable
logic-gates similar to the logic at the core of today's computers. This
framework had a limited impact on neuroscience, since neurons exhibit far
richer dynamics. Here we propose a new experimentally corroborated paradigm in
which the truth tables of the brain's logic-gates are time dependent, i.e.
dynamic logicgates (DLGs). The truth tables of the DLGs depend on the history
of their activity and the stimulation frequencies of their input neurons. Our
experimental results are based on a procedure where conditioned stimulations
were enforced on circuits of neurons embedded within a large-scale network of
cortical cells in-vitro. We demonstrate that the underlying biological
mechanism is the unavoidable increase of neuronal response latencies to ongoing
stimulations, which imposes a nonuniform gradual stretching of network delays.
The limited experimental results are confirmed and extended by simulations and
theoretical arguments based on identical neurons with a fixed increase of the
neuronal response latency per evoked spike. We anticipate our results to lead
to better understanding of the suitability of this computational paradigm to
account for the brain's functionalities and will require the development of new
systematic mathematical methods beyond the methods developed for traditional
Boolean algebra.Comment: 32 pages, 14 figures, 1 tabl
From FPGA to ASIC: A RISC-V processor experience
This work document a correct design flow using these tools in the Lagarto RISC- V Processor and the RTL design considerations that must be taken into account, to move from a design for FPGA to design for ASIC
Monolithically Patterned Wide-Narrow-Wide All-Graphene Devices
We investigate theoretically the performance advantages of all-graphene
nanoribbon field-effect transistors (GNRFETs) whose channel and source/drain
(contact) regions are patterned monolithically from a two-dimensional single
sheet of graphene. In our simulated devices, the source/drain and interconnect
regions are composed of wide graphene nanoribbon (GNR) sections that are
semimetallic, while the channel regions consist of narrow GNR sections that
open semiconducting bandgaps. Our simulation employs a fully atomistic model of
the device, contact and interfacial regions using tight-binding theory. The
electronic structures are coupled with a self-consistent three-dimensional
Poisson's equation to capture the nontrivial contact electrostatics, along with
a quantum kinetic formulation of transport based on non-equilibrium Green's
functions (NEGF). Although we only consider a specific device geometry, our
results establish several general performance advantages of such monolithic
devices (besides those related to fabrication and patterning), namely the
improved electrostatics, suppressed short-channel effects, and Ohmic contacts
at the narrow-to-wide interfaces.Comment: 9 pages, 11 figures, 2 table
Power reduction techniques for memory elements
High performance and computational capability in the current generation processors are made possible by small feature sizes and high device density. To maintain the current drive strength and control the dynamic power in these processors, simultaneous scaling down of supply and threshold voltages is performed. High device density and low threshold voltages result in an increase in the leakage current dissipation. Large on chip caches are integrated onto the current generation processors which are becoming a major contributor to total leakage power. In this work, a novel methodology is proposed to minimize the leakage power and dynamic power. The proposed static power reduction technique, GALEOR (GAted LEakage transistOR), introduces stacks by placing high threshold voltage transistors and consists of inherent control logic. The proposed dynamic power reduction technique, adaptive phase tag cache, achieves power savings through varying tag size for a design window. Testing and verification of the proposed techniques is performed on a two level cache system. Power delay squared product is used as a metric to measure the effectiveness of the proposed techniques. The GALEOR technique achieves 30% reduction when implemented on CMOS benchmark circuits and an overall leakage savings of 9% when implemented on the two level cache systems. The proposed dynamic power reduction technique achieves 10% savings when implemented on individual modules of the two level cache and an overall savings of 3% when implemented on the entire two level cache system
- …