Design of a low-voltage CMOS RF receiver for energy harvesting sensor node

In this thesis a CMOS low-power and low-voltage RF receiver front-end is presented. The main objective is to design this RF receiver so that it can be powered by a piezoelectric energy harvesting power source, included in a Wireless Sensor Node application. For this type of applications the major requirements are: the low-power and low-voltage operation, the reduced area and cost and the simplicity of the architecture. The system key blocks are the LNA and the mixer, which are studied and optimized with greater detail, achieving a good linearity, a wideband operation and a reduced introduction of noise. A wideband balun LNA with noise and distortion cancelling is designed to work at a 0.6 V supply voltage, in conjunction with a double-balanced passive mixer and subsequent TIA block. The passive mixer operates in current mode, allowing a minimal introduction of voltage noise and a good linearity. The receiver analog front-end has a total voltage conversion gain of 31.5 dB, a 0.1 - 4.3 GHz bandwidth, an IIP3 value of -1.35 dBm, and a noise figure lower than 9 dB. The total power consumption is 1.9 mW and the die area is 305x134.5 m2, using a standard 130 nm CMOS technology.

Machine ethics via logic programming

Machine ethics is an interdisciplinary field of inquiry that emerges from the need of imbuing autonomous agents with the capacity of moral decision-making. While some approaches provide implementations in Logic Programming (LP) systems, they have not exploited LP-based reasoning features that appear essential for moral reasoning. This PhD thesis aims at investigating further the appropriateness of LP, notably a combination of LP-based reasoning features, including techniques available in LP systems, to machine ethics. Moral facets, as studied in moral philosophy and psychology, that are amenable to computational modeling are identified, and mapped to appropriate LP concepts for representing and reasoning about them. The main contributions of the thesis are twofold. First, novel approaches are proposed for employing tabling in contextual abduction and updating – individually and combined – plus a LP approach of counterfactual reasoning; the latter being implemented on top of the aforementioned combined abduction and updating technique with tabling. They are all important to model various issues of the aforementioned moral facets. Second, a variety of LP-based reasoning features are applied to model the identified moral facets, through moral examples taken off-the-shelf from the morality literature. These applications include: (1) Modeling moral permissibility according to the Doctrines of Double Effect (DDE) and Triple Effect (DTE), demonstrating deontological and utilitarian judgments via integrity constraints (in abduction) and preferences over abductive scenarios; (2) Modeling moral reasoning under uncertainty of actions, via abduction and probabilistic LP; (3) Modeling moral updating (that allows other – possibly overriding – moral rules to be adopted by an agent, on top of those it currently follows) via the integration of tabling in contextual abduction and updating; and (4) Modeling moral permissibility and its justification via counterfactuals, where counterfactuals are used for formulating DDE.

8-Phase Ring oscillator for modern receivers

The evolution of receiver architectures, built in modern CMOS technologies, allows the design of high efficient receivers. A key block in modern receivers is the oscillator. The main objective of this thesis is to design a very low power and low area 8-Phase Ring Oscillator for biomedical applications (ISM and WMTS bands). Oscillators with multiphase outputs and variable duty cycles are required. In this thesis we are focused in 12.5% and 50% duty-cycles approaches. The proposed circuit uses eight inverters in a ring structure, in order to generate the output duty cycle of 50%. The duty cycle of 1/8 is achieved through the combination of the longer duty cycle signals in pairs, using, for this purpose, NAND gates. Since the general application are not only the wireless communications context, as well as industrial, scientific and medical plans, the 8-Phase Oscillator is simulated to be wideband between 100 MHz and 1 GHz, and be able to operate in the ISM bands (447 MHz-930 MHz) and WMTS (600 MHz). The circuit prototype is designed in UMC 130 nm CMOS technology. The maximum value of current drawn from a DC power source of 1.2 V, at a maximum frequency of 930 MHz achieved, is 17.54 mA. After completion of the oscillator layout studied (occupied area is 165 μm x 83 μm). Measurement results confirm the expected operating range from the simulations, and therefore, that the oscillator fulfil effectively the goals initially proposed in order to be used as Local Oscillator in RF Modern Receivers.

Quadrature generators based on ring oscillators and shift registers

Quadrature oscillators are key elements in modern radio frequency (RF) transceivers and very useful nowadays in wireless communications, since they can provide: low quadrature error, low phase-noise, and wide tuning range (useful to cover several bands). RC oscillators can be fully integrated without the need of external components (external high Q-inductors), optimizing area, cost, and power consumption. The conventional structure of ring oscillator offers poor frequency stability and phasenoise, low quality factor (Q), and besides being vulnerable to process, voltage and temperature (PVT) variations, its performance degrades as the frequency of operation increases. This thesis is devoted to quadrature oscillators and presents a detailed comparative study of ring oscillator and shift register (SR) approaches. It is shown that in SRs both phase-noise and phase error are reduced, while ring oscillators have the advantage of occupying less area and less consumption due to the reduced number of components in the circuit. Thus, although ring oscillators are more suitable for biomedical applications, SRs are more appropriate for wireless applications, especially when specification requirements are more stringent and demanding. The first architecture studied consists in a simple CMOS ring oscillator employing an odd number of static single-ended inverters as delay cells. Subsequently, the quadrature 4-stage ring oscillator concept is shown and post-layout simulations are presented. The 3 and 4-phase single-frequency local oscillator (LO) generators employing SRs are presented, the latter with 50% and 25% duty-cycles. The circuits operate at 600 MHz and 900 MHz, and were designed in a 130 nm standard CMOS technology with a voltage supply of 1.2 V.

Reconfigurable photonic logic architecture

The amorphous silicon photo-sensor studied in this thesis, is a double pin structure (p(a-SiC:H)-i’(a-SiC:H)-n(a-SiC:H)-p(a-SiC:H)-i(a-Si:H)-n(a-Si:H)) sandwiched between two transparent contacts deposited over transparent glass thus with the possibility of illumination on both sides, responding to wave-lengths from the ultra-violet, visible to the near infrared range. The frontal il-lumination surface, glass side, is used for light signal inputs. Both surfaces are used for optical bias, which changes the dynamic characteristics of the photo-sensor resulting in different outputs for the same input. Experimental studies were made with the photo-sensor to evaluate its applicability in multiplexing and demultiplexing several data communication channels. The digital light sig-nal was defined to implement simple logical operations like the NOT, AND, OR, and complex like the XOR, MAJ, full-adder and memory effect. A pro-grammable pattern emission system was built and also those for the validation and recovery of the obtained signals. This photo-sensor has applications in op-tical communications with several wavelengths, as a wavelength detector and to execute directly logical operations over digital light input signals.

Wideband CMOS low noise amplifiers

Modern fully integrated receiver architectures, require inductorless circuits to achieve their potential low area, low cost, and low power. The low noise amplifier (LNA), which is a key block in such receivers, is investigated in this thesis. LNAs can be either narrowband or wideband. Narrowband LNAs use inductors and have very low noise figure, but they occupy a large area and require a technology with RF options to obtain inductors with high Q. Recently, wideband LNAs with noise and distortion cancelling, with passive loads have been proposed, which can have low NF, but have high power consumption. In this thesis the main goal is to obtain a very low area, low power, and low-cost wideband LNA. First, it is investigated a balun LNA with noise and distortion cancelling with active loads to boost the gain and reduce the noise figure (NF). The circuit is based on a conventional balun LNA with noise and distortion cancellation, using the combination of a common-gate (CG) stage and common-source (CS) stage. Simulation and measurements results, with a 130 nm CMOS technology, show that the gain is enhanced by about 3 dB and the NF is reduced by at least 0.5 dB, with a negligible impact on the circuit linearity (IIP3 is about 0 dBm). The total power dissipation is only 4.8 mW, and the active area is less than 50 x 50 m2 . It is also investigated a balun LNA in which the gain is boosted by using a double feedback structure.We propose to replace the load resistors by active loads, which can be used to implement local feedback loops (in the CG and CS stages). This will boost the gain and reduce the noise figure (NF). Simulation results, with the same 130 nm CMOS technology as above, show that the gain is 24 dB and NF is less than 2.7 dB. The total power dissipation is only 5.4 mW (since no extra blocks are required), leading to a figure-of-merit (FoM) of 3.8 mW

Logic programming and artificial neural networks in breast cancer detection

About 90% of breast cancers do not cause or are capable of producing death if detected at an early stage and treated properly. Indeed, it is still not known a specific cause for the illness. It may be not only a beginning, but also a set of associations that will determine the onset of the disease. Undeniably, there are some factors that seem to be associated with the boosted risk of the malady. Pondering the present study, different breast cancer risk assessment models where considered. It is our intention to develop a hybrid decision support system under a formal framework based on Logic Programming for knowledge representation and reasoning, complemented with an approach to computing centered on Artificial Neural Networks, to evaluate the risk of developing breast cancer and the respective Degree-of-Confidence that one has on such a happening.

Implementação de um sistema MPPT em circuito integrado CMOS

Dissertação de mestrado integrado em Engenharia Eletrónica Industrial e Computadores

Evaluation of the determinism of the actuator sensor interface (ASI) on programmable logic controllers (PLC), personal computers (PC) and real-time operating systems (RTOS)

The purpose of this study was to evaluate the determinism of the AS-lnterface network and the 3 main families of control systems, which may use it, namely PLC, PC and RTOS. During the course of this study the PROFIBUS and Ethernet field level networks were also considered in order to ensure that they would not introduce unacceptable latencies into the overall control system. This research demonstrated that an incorrectly configured Ethernet network introduces unacceptable variable duration latencies into the control system, thus care must be exercised if the determinism of a control system is not to be compromised. This study introduces a new concept of using statistics and process capability metrics in the form of CPk values, to specify how suitable a control system is for a given control task. The PLC systems, which were tested, demonstrated extremely deterministic responses, but when a large number of iterations were introduced in the user program, the mean control system latency was much too great for an AS-I network. Thus the PLC was found to be unsuitable for an AS-I network if a large, complex user program Is required. The PC systems, which were tested were non-deterministic and had latencies of variable duration. These latencies became extremely exaggerated when a graphing ActiveX was included in the control application. These PC systems also exhibited a non-normal frequency distribution of control system latencies, and as such are unsuitable for implementation with an AS-I network. The RTOS system, which was tested, overcame the problems identified with the PLC systems and produced an extremely deterministic response, even when a large number of iterations were introduced in the user program. The RTOS system, which was tested, is capable of providing a suitable deterministic control system response, even when an extremely large, complex user program is required.

Towards flexible feature composition : static and dynamic binding in software product lines

Magdeburg, Univ., Fak. für Informatik, Diss., 2011

Static and dynamic interpretations of hand specific body language cues for HCI

Otto-von-Guericke-Universität Magdeburg, Fakultät für Elektrotechnik und Informationstechnik, Univ., Dissertation, 2015

Static diffusion models of the upper atmosphere with empirical temperature profiles.

v. 8 no. 9

Regulación del proceso de secado de embutidos crudos-curados mediante la aplicación de lógica borrosa (fuzzy logic)

El presente proyecto tenía como objetivo final el desarrollo de un sistema de control basado en Lógica Fuzzy que permita que el proceso de secado tenga una regulación continua y con una menor dependencia de la experiencia del personal experto, evitando además la formación de encostrado. Asimismo, se plantearon una serie de objetivos parciales, cuya consecución permitiría, además de alcanzar el objetivo final descrito, obtener un conocimiento científico adicional. Por ello, a continuación se resumen los resultados en relación con los objetivos parciales propuestos. Como paso previo, antes de abordar los objetivos planteados se diseñó y construyó un equipo experimental de secado, donde se controló de forma precisa la temperatura, la humedad relativa y la velocidad del aire.

Static and dynamic shoulder stabilizer adaptations in javelin throwers: A preliminary study

BACKGROUND: Adaptations to Internal (IR) and external (ER) rotator shoulder muscles improving overhead throwing kinematics could lead to muscular strength imbalances and be considered an intrinsic risk factor for shoulder injury, as well as modified shoulder range of motion (RoM). OBJECTIVE: To establish profiles of internal and external rotation RoM and isokinetic IR and ER strength in adolescent- and national-level javelin throwers. METHODS: Fourteen healthy subjects were included in this preliminary cross-sectional study, 7 javelin throwers (JTG) and 7 nonathletes (CG). Passive internal and external rotation RoM were measured at 90 degrees of shoulder abduction. Isokinetic strength of dominant and non-dominant IR and ER was evaluated during concentric (60, 120 and 240 degrees/s) and eccentric (60 degrees/s) contractions by Con-Trex (R) dynamometer with the subject in a seated position with 45 degrees of shoulder abduction in the scapular plane. RESULTS: We reported significantly lower internal rotation and significantly higher external rotation RoM in JTG than in CG. Concentric and eccentric IR and ER strength were significantly higher for the dominant shoulder side in JTG (P < 0.05), without significant differences in ER/IR ratios. CONCLUSIONS: The main finding of this preliminary study confirmed static and dynamic shoulder stabilizer adaptations due to javelin throw practice in a population of adolescent- and national-level javelin throwers.

Caracterització d'oscil·ladors basats en CMOS-M/NEMS i la seva aplicació com a sensors de massa

El present projecte tracta sobre la caracterització d'oscil·ladors basats en ressonadors micro/nanoelectromecànics (M/NEMS) i la seva aplicació com a sensors de massa. Els oscil·ladors utilitzats es basen en un pont i una palanca ressoants M/NEMS, integrats en tecnologia CMOS. En primer lloc s'ha fet una introducció teòrica als conceptes utilitzats per a entendre el funcionament i la caracterització dels dispositius. A continuació s'han realitzat proves per tal de caracteritzar els paràmetres importants per a l'ús dels oscil·ladors com a sensors de massa, com la seva estabilitat en freqüència. Per acabar s'han aplicat aquests sensors en la caracterització i modelització del flux de massa a través d'obertures de dimensions micromètriques.