Browsing by Author "Rubio, Antonio"

Now showing 1 - 4 of 4
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    A Digital Memristor Emulator for FPGA-Based Artificial Neural Networks
    (IEEE, 2016) Vourkas, Ioannis; Abusleme Hoffman, Ángel Christian; Ntinas, Vasileios; Sirakoulis, Georgios C.; Rubio, Antonio
    FPGAs are reconfigurable electronic platforms, well-suited to implement complex artificial neural networks (ANNs). To this end, the compact hardware (HW) implementation of artificial synapses is an important step to obtain human brain-like functionalities at circuit-level. In this context, the memristor has been proposed as the electronic analogue of biological synapses, but the price of commercially available samples still remains high, hence motivating the development of HW emulators. In this work we present the first digital memristor emulator based upon a voltage-controlled threshold-type bipolar memristor model. We validate its functionality in low-cost yet powerful FPGA families. We test its suitability for complex memristive circuits and prove its synaptic properties in a small associative memory via a perceptron ANN.
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    Experimental Study of Artificial Neural Networks Using a Digital Memristor Simulator
    (2018) Ntinas, Vasileios; Vourkas, Ioannis; Abusleme Hoffman, Ángel Christian; Sirakoulis Georgios Ch.; Rubio, Antonio
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    Exploring the voltage divider approach for accurate memristor state tuning
    (IEEE, 2017) Vourkas, Ioannis; Gómez Luna, Jorge Antonio; Abusleme Hoffman, Ángel Christian; Vasileiadis, Nikolaos; Sirakoulis, Georgios C.; Rubio, Antonio
    The maximum exploitation of the favorable properties and the analog nature of memristor technology in future nonvolatile resistive memories, requires accurate multi-level programming. In this direction, we explore the voltage divider (VD) approach for highly controllable multi-state SET memristor tuning. We present the theoretical basis of operation, the main advantages and weaknesses. We finally propose an improved closed-loop VD SET scheme to tackle the variability effect and achieve <;1% tuning precision, on average 3x faster than another accurate tuning algorithm of the recent literature.
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    Voltage Divider for Self-Limited Analog State Programing of Memristors
    (IEEE, 2020) Vourkas, Ioannis; Gómez, Jorge; Abusleme Hoffman, Ángel Christian; Sirakoulis, Georgios Ch.; Rubio, Antonio
    Resistive switching devices −memristors −present a tunable, incremental switching behavior. Tuning their state accurately, repeatedly and in a wide range, makes memristors well-suited for multi-level (ML) resistive memory cells and analog computing applications. In this brief, the tuning approach based on a memristor-resistor voltage divider (VD) is validated here experimentally using commercial memristors from Knowm Inc. and a custom circuit. Rapid and controllable multi-state SET tuning is shown with an appreciable range of different resistance values obtained as a function of the amplitude of the applied voltage pulse. The efficiency of the VD is finally compared against an adaptive pulse-based tuning protocol, in terms of circuit overhead, tuning precision, tuning time, and energy consumption, qualifying as a simple hardware solution for fast, reliable, and energy-efficient ML resistance tuning.