Consejo Superior de Investigaciones Científicas · Universidad de Sevilla
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Arrayable Voltage-Controlled Ring-Oscillator for Direct Time-of-Flight Image Sensors
I. Vornicu, R. Carmona-Galan and Rodriguez-Vazquez
Journal Paper - IEEE Transactions on Circuits and Systems I-Regular Papers, vol. 64, no. 11, pp 2821-2834, 2017
IEEE    DOI: 10.1109/TCSI.2017.2706324    ISSN: 1549-8328    » doi
[abstract]
Direct time-of-flight (d-ToF) estimation with high frame rate requires the incorporation of a time-to-digital converter (TDC) at pixel level. A feasible approach to a compact implementation of the TDC is to use the multiple phases of a voltage-controlled ring-oscillator (VCRO) for the finest bits. The VCRO becomes central in determining the performance parameters of a d-ToF image sensor. In this paper, we are covering the modeling, design, and measurement of a CMOS pseudo-differential VCRO. The oscillation frequency, the jitter due to mismatches and noise and the power consumption are analytically evaluated. This design has been incorporated into a 64x64-pixel array. It has been fabricated in a 0.18 mu m standard CMOS technology. Occupation area is 28x29 mu m(2) and power consumption is 1.17 mW at 850 MHz. The measured gain of the VCRO is of 477 MHz/V with a frequency tuning range of 53%. Moreover, it features a linearity of 99.4% over a wide range of control frequencies, namely, from 400 to 850 MHz. The phase noise is of -102 dBc/Hz at 2 MHz offset frequency from 850 MHz. The influence of these parameters in the performance of the TDC has been measured. The minimum time bin of the TDC is 147 ps with a rms DNL/INL of 0.13/1.7LSB.

Design of analog and mixed signal circuits with physical design and variability considerations
A. Toro-Frías
Thesis - Date of defense: 29/09/2017
UNIVERSIDAD DE SEVILLA, IMSE-CNM    
[abstract]
Abstract not avaliable

Dedicated Hardware for Embedded Vision Systems
E. Calvo-Gallego
Thesis - Date of defense: 18/09/2017
UNIVERSIDAD DE SEVILLA, IMSE-CNM    
[abstract]
Abstract not avaliable

Systematic Design of Reconfigurable Analog and Mixed Signal Circuits and Systems
M. Velasco-Jiménez
Thesis - Date of defense: 15/09/2017
UNIVERSIDAD DE SEVILLA, IMSE-CNM    
[abstract]
Abstract not avaliable

VLSI implementations of low-power Trivium stream ciphers
J.M. Mora-Gutiérrez
Thesis - Date of defense: 12/05/2017
UNIVERSIDAD DE SEVILLA, IMSE-CNM    
[abstract]
Abstract not avaliable

Passive localization and detection of quadcopter UAVs by using dynamic vision sensor
S. Hoseini, G. Orchard, A. Yousefzadeh, B. Deverakonda, T. Serrano-Gotarredona and B. Linares-Barranco
Conference - Iranian Joint Congress on Fuzzy and Intelligent Systems, Conference on Fuzzy Systems and Conference on Intelligent Systems CFIS 2017
[abstract]
We present a new passive and low power localization method for quadcopter UAVs (Unmanned aerial vehicles) by using dynamic vision sensors. This method works by detecting the speed of rotation of propellers that is normally higher than the speed of movement of other objects in the background. Dynamic vision sensors are fast and power efficient. We have presented the algorithm along with the results of implementation.

Event-Driven Stereo Visual Tracking Algorithm to Solve Object Occlusion
L.A. Camunas-Mesa, T. Serrano-Gotarredona, S. Ieng, R. Benosman and B. Linares-Barranco
Journal Paper - IEEE Transactions on Neural Networks and Learning Systems, first online, 2017
IEEE    DOI: 10.1109/TNNLS.2017.2759326    ISSN: 2162-237X    » doi
[abstract]
Object tracking is a major problem for many computer vision applications, but it continues to be computationally expensive. The use of bio-inspired neuromorphic event-driven dynamic vision sensors (DVSs) has heralded new methods for vision processing, exploiting reduced amount of data and very precise timing resolutions. Previous studies have shown these neural spiking sensors to be well suited to implementing single-sensor object tracking systems, although they experience difficulties when solving ambiguities caused by object occlusion. DVSs have also performed well in 3-D reconstruction in which event matching techniques are applied in stereo setups. In this paper, we propose a new event-driven stereo object tracking algorithm that simultaneously integrates 3-D reconstruction and cluster tracking, introducing feedback information in both tasks to improve their respective performances. This algorithm, inspired by human vision, identifies objects and learns their position and size in order to solve ambiguities. This strategy has been validated in four different experiments where the 3-D positions of two objects were tracked in a stereo setup even when occlusion occurred. The objects studied in the experiments were: 1) two swinging pens, the distance between which during movement was measured with an error of less than 0.5%; 2) a pen and a box, to confirm the correctness of the results obtained with a more complex object; 3) two straws attached to a fan and rotating at 6 revolutions per second, to demonstrate the high-speed capabilities of this approach; and 4) two people walking in a real-world environment.

Digital Implementation of the Two-Compartmental Pinsky-Rinzel Pyramidal Neuron Model
E. Rahimian, S. Zabihi, M. Amiri and B. Linares-Barranco
Journal Paper - IEEE Transactions on Biomedical Circuits and Systems, first online, 2017
IEEE    DOI: 10.1109/TBCAS.2017.2753541    ISSN: 1932-4545    » doi
[abstract]
It is believed that brain-like computing system can be achieved by the fusion of electronics and neuroscience. In this way, the optimized digital hardware implementation of neurons, primary units of nervous system, play a vital role in neuromorphic applications. Moreover, one of the main features of pyramidal neurons in cortical areas is bursting activities that has a critical role in synaptic plasticity. The Pinsky-Rinzel model is a nonlinear two-compartmental model for CA3 pyramidal cell that is widely used in neuroscience. In this paper, a modified Pinsky-Rinzel pyramidal model is proposed by replacing its complex nonlinear equations with piecewise linear approximation. Next, a digital circuit is designed for the simplified model to be able to implement on a low-cost digital hardware, such as field-programmable gate array (FPGA). Both original and proposed models are simulated in MATLAB and next digital circuit simulated in Vivado is compared to show that obtained results are in good agreement. Finally, the results of physical implementation on FPGA are also illustrated. The presented circuit advances preceding designs with regards to the ability to replicate essential characteristics of different firing responses including bursting and spiking in the compartmental model. This new circuit has various applications in neuromorphic engineering, such as developing new neuroinspired chips.

Vulnerability Analysis of Trivium FPGA Implementations
F.E. Potestad-Ordonez, C.J. Jimenez-Fernandez and M. Valencia-Barrero
Journal Paper - IEEE Transactions on Very Large Scale Integration (VLSI) Systems, first online, 2017
IEEE    DOI: 10.1109/TVLSI.2017.2751151    ISSN: 1063-8210    » doi
[abstract]
Today, the large amount of information ex-changed among various devices as well as the growth of the Internet of Things (IoT) demand the development of devices that ensure secure communications, preventing malicious agents from tapping sensitive data. Indeed, information security is one of the key challenges to address within the IoT field. Due to the strong resource constraints in some IoT applications, cryptographic algorithms affording lightweight implementations have been proposed. They constitute the so-called lightweight cryptography. A prominent example is the Trivium stream cipher, one of the finalists of the eSTREAM project. Although cryptographic algorithms are certainly simpler, one of their most critical vulnerability sources in terms of hardware implementations is side channel attacks. In this paper, it is studied the vulnerability of field-programmable gate array (FPGA) implementations of Trivium stream ciphers against fault attacks. The design and implementation of a system that alters the clock signal and checks the outcome is also described. A comparison between real and simulated fault injections is carried out in order to examine their veracity. The vulnerability of different versions of the Trivium cipher and their routing dependences has been tested in two different FPGA families. The results show that all versions of the Trivium cipher are vulnerable to fault attacks, although some versions are more vulnerable than others.

Sun sensor based on a luminance spiking pixel array
J.A. Lenero-Bardallo, L. Farian, J.M. Guerrero-Rodriguez, R. Carmona-Galan and A. Rodriguez-Vazquez
Journal Paper - IEEE Sensors Journal, vol. 17, no. 20, pp 6578-6588, 2017
IEEE    DOI: 10.1109/JSEN.2017.2749414    ISSN: 1530-437X    » doi
[abstract]
We present a novel sun sensor concept. It is the very first sun sensor built with an Address Event Representation (AER) spiking pixel matrix. Its pixels spike with a frequency proportional to illumination. It offers remarkable advantages over conventional digital sun sensors based on Active Pixel Sensor (APS) pixels. Its output data flow is quite reduced. It is possible to resolve the sun position just receiving one single event operating in Time-to-First-Spike (TFS) mode. It operates with a latency in the order of milliseconds. It has higher dynamic range than APS image sensors (higher than 100dB). A custom algorithm to compute the centroid of the illuminated pixels is presented. Experimental results are provided.

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