This paper deals with coupled oscillators as the building blocks of a bioinspired computing parad... more This paper deals with coupled oscillators as the building blocks of a bioinspired computing paradigm and their implementation. In order to accomplish the low-power and fast-processing requirements of autonomous applications, we study the microelectronic analog implementation of physical oscillators, instead of the software computer-simulated implementation. With this aim, the original oscillator has been adapted to a suitable microelectronic form. So as to study the hardware nonlinear oscillators, we propose two macro models, demonstrating that they preserve the synchronization properties. Secondary effects such as mismatch and output delay and their relation to network synchronization are analyzed and discussed. We show the correct operation of the proposed electronic oscillators with simulations and experimental results from a manufactured integrated test circuit. The proposed architecture is intended to perform the scene segmentation stage of an autonomous focal-plane self-contained visual processing system for artificial vision applications.
Students who enter university have been studying all their lives, but most of them have not been ... more Students who enter university have been studying all their lives, but most of them have not been taught how to do it. To study well, it is convenient to know how the human brain works. However, most teachers and students are unaware of the mechanisms used by the human brain to learn. This paper describes the main human brain learning-mechanisms, and provides some advice that students should follow to take advantage of these mechanisms. These tips include having healthy habits (appropriate eating, respecting sleep and circadian rhythms, and exercise), techniques to improve learning (Pomodoro, weekly planning, assessment training) and techniques to enhance mental abilities (Mindfulness, growth mindset and stoic techniques).
Complete nonlinear model for the MRC (MOS resistive circuit)
2000 IEEE International Symposium on Circuits and Systems. Emerging Technologies for the 21st Century. Proceedings (IEEE Cat No.00CH36353)
ABSTRACT The most significant sources of nonlinearity in the MOS resistive circuit behaviour are ... more ABSTRACT The most significant sources of nonlinearity in the MOS resistive circuit behaviour are identified and deeply analysed in this contribution. Their influence on the MRC performance and, therefore, in the circuits containing such structure is evidenced through some examples and evaluated. Some reasonable hints about the way to minimise their undesired effects are provided
Novel pulse-width-modulated current-mode defuzzifier for the fuzzy control of switching DC–DC converters
In this communication, the authors propose a current-mode analog circuit solution for the defuzzi... more In this communication, the authors propose a current-mode analog circuit solution for the defuzzifying step required for the fuzzyknowledge-based control (FKBC) of switching DC-DC converters. Considering the modulation of pulse widths which is needed for the control of switched power plants, the division operation at the output layer of a fuzzy inference controller takes advantage of the implicit signal-to-time conversion in the PWM process. This theoretical aspect is complemented with the proposal of a high-speed current-mode division circuit, which allows a wide range of switching frequencies. The PWM division circuit is preceded by a switched-current integrator to obtain a full defuzzifier. HSPICE layout-extracted transistor-level simulations for a standard CMOS 0.8μm technology verify the functionality of both the proposed defuzzifying method and circuit.
Analog Integrated Circuits and Signal Processing, 2004
A novel CMOS variable gain amplifier operating on current signals with a dB-linear gain control i... more A novel CMOS variable gain amplifier operating on current signals with a dB-linear gain control is presented. The gain control is achieved by multiplying a digitally synthesized exponentially varying control current signal by a differential input signal in the current domain. A current amplifier at the output sets the gain to the desired level. Current-mode operation allows for a reduced supply voltage by minimizing the voltage swing at the low impedance nodes of the circuit. Multiple circuit realizations for various blocks are presented allowing for designs meeting different constraints. Experimental realization of the variable gain amplifier shows the validity of the presented approach.
Analog Integrated Circuits and Signal Processing, 2004
Dynamic modelling of analog integrated filters for the stability study of on-chip automatic tuning loops
IEEE International Symposium on Circuits and Systems proceedings, 2004
ABSTRACT Continuous-time filters with automatic tuning loops are feedback nonlinear systems with ... more ABSTRACT Continuous-time filters with automatic tuning loops are feedback nonlinear systems with potential instability. If a stability study is to be carried out, even if it is at least local, the appropriate linear dynamical modelling of the filter should be obtained. This modelling is mandatory if an improved design of the loop controllers is to be carried out. This work presents the dynamic modelling of a CMOS continuous-time analog filter with automatic tuning capability. The analysis leads to an equivalent small-signal linearised incremental model from which transfer functions between output variables and control voltages are obtained. The dynamic modelling of both the phase-shift between input and output signals as well as the output amplitude, required to properly tune both frequency and quality factor parameters, is presented. The analysis leads to the design of a compensated loop with enhanced stability and dynamic performance.
SystemC-WMS modeling of control techniques for switching amplifiers targeting polar RF transmitters
This device is designed to cover and prevent a hypodermic needle in a syringe from possibly scrat... more This device is designed to cover and prevent a hypodermic needle in a syringe from possibly scratching a person after it has been used and discarded, which will help prevent spread of contagious diseases. Primarily, it consists of a transparent sleeve that receives the barrel of a hypodermic syringe, and after the needle has been used, the sleeve is pushed forward to cover the needle. The sleeve and the barrel of the syringe cooperate with each other to lock in the forward and needle covering position, by having a self-contained locking mechanism.
Following its use to define a particular approach to monolithic analog circuit design, in the lat... more Following its use to define a particular approach to monolithic analog circuit design, in the late sixties, the "current-mode" perspective aroused increasing interest for several years, as a novel and possibly useful point of view. During the vacuum-tube era such an approach to the realization of a function was rarely, if ever, employed. This can be attributed partly to history, and to the nature of a tube, which is a voltage-controlled current-source. In the early applications of the bipolar junction transistor (BJT) it was viewed (improperly) as some sort of "current mode amplifier", having a common-emitter "gain" of beta (I C /I B). Consequently, circuit design shifted emphasis to make better use of this new property. Discrete BJTs were therefore biased using a small base current, because the "tube paradigm" (driving them with a fixed base-emitter voltage) was impractical, due to the very large temperature-coefficient of the voltage required (V BE) to reliably establish a certain current. Textbooks sensibly advised: "For this reason it is usually not profitable to bias (or try to bias) the input port directly by means of a voltage source." 1 The drive needs to be very carefully controlled: an 18 mV error will alter the current by a factor of two, and by much more when the transistor's self-heating is significant. This behavior was the cause of a new phenomenon, "thermal runaway", which took some time to tame. Later, the same solution (emitter degeneration) was applied to small-signal amplifiers, to set their operating point, but now using a voltage drive. With the advent of monolithic IC processes, new solutions were found. The current mirror addressed the problem by using a second, diode-connected currentdriven transistor to generate this critical voltage. This combination provided a temperature-stable output current, with the further general utility of it being closely proportional to the input current. The current mirror provided the first example of IC current-mode design, made possible because of the assumption of isothermal operation of all transistors in a monolithic cell. Its current ratio accuracy was assured by the second cornerstone of monolithic design, namely, that geometrically-similar transistors are closely matched, particularly in their V BE (I C , T) behavior. This new way to manage the temperature
Hysteric controller for CMOS on-chip switching power converters
2004 IEEE International Symposium on Circuits and Systems (IEEE Cat. No.04CH37512), 2004
... IEEE International Symposium on Industrial Electronics, ISIE'99, pp. 601. 15. ... 25. S.... more ... IEEE International Symposium on Industrial Electronics, ISIE'99, pp. 601. 15. ... 25. S. Ajram, G. Salmer, "Ultrahigh Frequency DC-to-DC Converters Using GaAs Power Switches", IEEE Transactions on Power Electronics, pp. 594-602. September 2001. 26. ...
Synchronizable Compact CMOS Oscillator
Analog Integrated Circuits and Signal Processing, 2005
This letter describes the design and implementation of a synchronizable compact CMOS oscillator. ... more This letter describes the design and implementation of a synchronizable compact CMOS oscillator. By using a fully differential topology, a reduction in area occupancy together with an improved robustness in front of on-chip interferences is achieved. Post-layout simulation results and experimental results for a standard CMOS 0.35 µ m technology are presented to validate the functionality of the tunable oscillator.
Dynamic modeling of tunable analog integrated filters for a stability study of on-chip automatic tuning loops
Analog Integrated Circuits and Signal Processing, 2009
Continuous-time filters with automatic tuning loops are nonlinear feedback systems that are poten... more Continuous-time filters with automatic tuning loops are nonlinear feedback systems that are potentially unstable. To ensure stability, particularly if the design of the loop controllers is to be improved, the appropriate linear dynamic modeling of the tunable filter, including control inputs, should be attained. This work aims to present a general dynamic modeling of continuous-time analog filters with automatic tuning
This paper presents three tools developed within the framework of the project EDINSOST2-SDG, aime... more This paper presents three tools developed within the framework of the project EDINSOST2-SDG, aimed at embedding and assessing the Education for Sustainable Development (ESD) in Engineering curricula. ESD is promoted through the introduction into engineering curricula of learning outcomes related to sustainability and, specifically, to the Sustainable Development Goals (SDG). The first tool, the “Engineering Sustainability Map”, contains ESD-related learning outcomes that any engineering student should have acquired upon completion of their studies. These learning outcomes are described according to four sustainability competencies: (1) Critical contextualization of knowledge, (2) Sustainable use of resources, (3) Participation in community processes, and (4) Application of ethical principles. The second tool, the “Sustainability Presence Map” of a degree, shows the percentage of the presence in the curriculum of each sustainability competency. The calculation of the presence of each...
This Research to Practice Work in Progress paper presents the work conducted on the use of the Su... more This Research to Practice Work in Progress paper presents the work conducted on the use of the Sustainability Map of Bachelor Engineering Degrees (a tool developed by the EDINSOST project) to analyze how Sustainable Development Goals (SDGs) are developed in each Degree. Over recent years, there has been a growth in the importance of working sustainability based on the SDGs. To identify which learning objective of each SDG corresponds to each learning outcome of the EDINSOST Sustainability Map, a correspondence matrix has been defined. The matrix contains the learning outcomes of the EDINSOST Sustainability Map in its rows, and the 17 SDGs in the columns. The cells of the matrix contain the learning objectives of the SDGs that correspond to each learning outcome of the EDINSOST Sustainability Map. This work in progress presents the first results of the process of mapping the SDGs into the EDINSOST Sustainability Map of Engineering Bachelor Degrees. Early results show that some of the 169 learning objectives are not applicable to Engineering Degrees. Likewise, we have seen that learning objectives have been defined more for policy makers than for engineers, and therefore adaptation is not an easy task. However, the work done has helped us to verify that the EDINSOST Sustainability Map can help in the introduction of the SDGs into the curriculum.
Machine learning systems have become ubiquitous into our society. This has raised concerns about ... more Machine learning systems have become ubiquitous into our society. This has raised concerns about the potential discrimination that these systems might exert due to unconscious bias present in the data, for example regarding gender and race. Whilst this issue has been proposed as an essential subject to be included in the new AI curricula for schools, research has shown that it is a difficult topic to grasp by students. We propose an educational platform tailored to raise the awareness of gender bias in supervised learning, with the novelty of using Grad-CAM as an explainability technique that enables the classifier to visually explain its own predictions. Our study demonstrates that preadolescents (N=78, age 10-14) significantly improve their understanding of the concept of bias in terms of gender discrimination, increasing their ability to recognize biased predictions when they interact with the interpretable model, highlighting its suitability for educational programs. CCS CONCEPTS • Human-centered computing → Empirical studies in HCI; • Applied computing → Interactive learning environments; • Computing methodologies → Machine learning; Artificial intelligence.
It is vital that subjects such as the circular economy, sustainable design, green computing or en... more It is vital that subjects such as the circular economy, sustainable design, green computing or environmental engineering be included in the engineering curriculum. Education for sustainable development will enable engineers to develop sustainable products and provide sustainable services, thereby leading to a beneficial result for society and making an indispensable contribution to the Sustainable Development Goals achievement. As the last stage for students in academia, Degree Theses (Bachelor’s and Master’s) provide a good tool for reviewing the sustainability competencies developed during the degree, as well as being an opportunity for applying these competencies in a holistic way. In their Degree Theses, students should be able to demonstrate that they are aware of the need to introduce and assess sustainability in their future engineering projects. This paper presents a guide aimed at helping engineering students to design and develop sustainable projects, and analyzes the firs...
2016 IEEE Frontiers in Education Conference (FIE), 2016
This paper presents a tool we have developed to help engineers to design and develop sustainable ... more This paper presents a tool we have developed to help engineers to design and develop sustainable projects. The tool has been designed to introduce and evaluate the sustainability of engineering projects in general, but here we present how it can be applied to assess the final project of an engineering degree. This tool is a guide for students to introduce and estimate the sustainability of their projects, but it also helps teachers to assess them. The tool is based on the Socratic Methodology and consists of a matrix where each cell contains several questions that students must consider during the project development and which they must answer in their project report. A positive or negative mark is assigned to every cell, and the sum of all marks states the project sustainability. However, the result is not as simplistic as a final number, but a descriptive sustainability analysis where all questions are answered and every mark justified. A pilot test with some students has obtained good results, but the first Final Degree Project using the proposed methodology will be read in July 2016.
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Papers by Eva Vidal