Logic functions based on optical bias controlled SIC Tandem devices

The purpose of this paper is the design of an optoelectronic circuit based on a-SiC technology, able to act simultaneously as a 4-bit binary encoder or a binary decoder in a 4-to-16 line configurations and show multiplexer-based logical functions. The device consists of a p-i'(a-SiC:H)-n/p-i(a-Si:H)-n multilayered structure produced by PECVD. To analyze it under information-modulated wave (color channels) and uniform irradiation (background) four monochromatic pulsed lights (input channels): red, green, blue and violet shine on the device. Steady state optical bias was superimposed separately from the front and the back sides, and the generated photocurrent was measured. Results show that the devices, under appropriate optical bias, act as reconfigurable active filters that allow optical switching and optoelectronic logic functions development providing the possibility for selective removal of useless wavelengths. The logic functions needed to construct any other complex logic functions are the NOT, and both or either an AND or an OR. Any other complex logic function that might be found can also be used as building blocks to achieve the functions needed for the retrieval of channels within the WDM communication link. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

ROM-less RNS-to-binary converter moduli {22N − 1, 22N + 1, 2N − 3, 2N + 3}

In this paper, a novel ROM-less RNS-to-binary converter is proposed, using a new balanced moduli set {22n-1, 22n + 1, 2n-3, 2n + 3} for n even. The proposed converter is implemented with a two stage ROM-less approach, which computes the value of X based only in arithmetic operations, without using lookup tables. Experimental results for 24 to 120 bits of Dynamic Range, show that the proposed converter structure allows a balanced system with 20% faster arithmetic channels regarding the related state of the art, while requiring similar area resources. This improvement in the channel's performance is enough to offset the higher conversion costs of the proposed converter. Furthermore, up to 20% better Power-Delay-Product efficiency metric can be achieved for the full RNS architecture using the proposed moduli set. © 2014 IEEE.

SiC pinpin photonic for linking the visible spectrum to the telecom gap

Expanding far beyond traditional applications at telecommunications wavelengths, the SiC photonic devices has recently proven its merits for working with visible range optical signals. Reconfigurable wavelength selectors are essential sub-systems for implementing reconfigurable WDM networks and optical signal processing. Visible range to telecom band spectral translation in SiC/Si can be accomplished using wavelength selector under appropriated optical bias, acting as reconfigurable active filters. In this paper we present a monolithically integrated wavelength selector based on a multilayer SiC/Si integrated optical filters that requires optical switches to select wavelengths. The selector filter is realized by using double pin/pin a-SiC:H photodetector with front and back biased optical gating elements. Red, green, blue and violet communication channels are transmitted together, each one with a specific bit sequence. The combined optical signal is analyzed by reading out the generated photocurrent, under different background wavelengths applied either from the front or the back side. The backgrounds acts as channel selectors that selects one or more channels by splitting portions of the input multi-channel optical signals across the front and back photodiodes. The transfer characteristics effects due to changes in steady state light, irradiation side and frequency are presented. The relationship between the optical inputs and the digital output levels is established. (C) 2014 Elsevier B.V. All rights reserved.

Tunnig optical A-Sic/A-Si active filters by UV bias light in the visible and infrared spectral ranges

Visible range to telecom band spectral translation is accomplished using an amorphous SiC pi'n/pin wavelength selector under appropriate front and back optical light bias. Results show that background intensity works as selectors in the infrared region, shifting the sensor sensitivity. Low intensities select the near-infrared range while high intensities select the visible part according to its wavelength. Here, the optical gain is very high in the infrared/red range, decreases in the green range, stays close to one in the blue region and strongly decreases in the near-UV range. The transfer characteristics effects due to changes in steady state light intensity and wavelength backgrounds are presented. The relationship between the optical inputs and the output signal is established. A capacitive optoelectronic model is presented and tested using the experimental results. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light-activated amplification in SiC Tandem devices: A capacitive active filter model

Characteristics of tunable wavelength pi'n/pin filters based on a-SiC:H multilayered stacked cells are studied both experimentally and theoretically. Results show that the device combines the demultiplexing operation with the simultaneous photodetection and self amplification of the signal. An algorithm to decode the multiplex signal is established. A capacitive active band-pass filter model is presented and supported by an electrical simulation of the state variable filter circuit. Experimental and simulated results show that the device acts as a state variable filter. It combines the properties of active high-pass and low-pass filter sections into a capacitive active band-pass filter using a changing capacitance to control the power delivered to the load.

Optical nonlinearity in Tandem SI-C photodetectors

The behavior of tandem pin heterojunctions based on a-SiC: H alloys is investigated under different optical and electrical bias conditions. The devices are optimized to act as optically selective wavelength filters. Depending on the device configuration (optical gaps, thickness, sequence of cells in the stack structure) and on the applied voltage (positive or negative) and optical bias (wavelength, intensity, frequency) it is possible to combine the wavelength discrimination function with the self amplification of the signal. This wavelength nonlinearity allows the amplification or the rejection of a weak signal-impulse. The device works as an active tunable optical filter for wavelength selection and can be used as an add/drop multiplexer (ADM) which enables data to enter and leave an optical network bit stream without having to demultiplex the stream. Results show that, even under weak transient input signals, the background wavelength controls the output signal. This nonlinearity, due to the transient asymmetrical light penetration of the input channels across the device together with the modification on the electrical field profile due to the optical bias, allows tuning an input channel without demultiplexing the stream. This high optical nonlinearity makes the optimized devices attractive for the amplification of all optical signals. Transfer characteristics effects due to changes in steady state light, control d.c. voltage and applied light pulses are presented. Based on the experimental results and device configuration an optoelectronic model is developed. The transfer characteristics effects due to changes in steady state light, dc control voltage or applied light pulses are simulated and compared with the experimental data. A good agreement was achieved.

High-performance flexible hybrid field-effect transistors based on cellulose fiber paper

IEEE Electron Device Letters, VOL. 29, NO. 9,

Transístores de efeito de campo de silício cristalino obtidos pelo método de pré-deposição de dopante a baixa temperatura

Dissertação para obtenção do Grau de Mestre em Engenharia de Materiais

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.

Analysis and design of sinusoidal quadrature RC-oscillators

Modern telecommunication equipment requires components that operate in many different frequency bands and support multiple communication standards, to cope with the growing demand for higher data rate. Also, a growing number of standards are adopting the use of spectrum efficient digital modulations, such as quadrature amplitude modulation (QAM) and orthogonal frequency division multiplexing (OFDM). These modulation schemes require accurate quadrature oscillators, which makes the quadrature oscillator a key block in modern radio frequency (RF) transceivers. The wide tuning range characteristics of inductorless quadrature oscillators make them natural candidates, despite their higher phase noise, in comparison with LC-oscillators. This thesis presents a detailed study of inductorless sinusoidal quadrature oscillators. Three quadrature oscillators are investigated: the active coupling RC-oscillator, the novel capacitive coupling RCoscillator, and the two-integrator oscillator. The thesis includes a detailed analysis of the Van der Pol oscillator (VDPO). This is used as a base model oscillator for the analysis of the coupled oscillators. Hence, the three oscillators are approximated by the VDPO. From the nonlinear Van der Pol equations, the oscillators’ key parameters are obtained. It is analysed first the case without component mismatches and then the case with mismatches. The research is focused on determining the impact of the components’ mismatches on the oscillator key parameters: frequency, amplitude-, and quadrature-errors. Furthermore, the minimization of the errors by adjusting the circuit parameters is addressed. A novel quadrature RC-oscillator using capacitive coupling is proposed. The advantages of using the capacitive coupling are that it is noiseless, requires a small area, and has low power dissipation. The equations of the oscillation amplitude, frequency, quadrature-error, and amplitude mismatch are derived. The theoretical results are confirmed by simulation and by measurement of two prototypes fabricated in 130 nm standard complementary metal-oxide-semiconductor (CMOS) technology. The measurements reveal that the power increase due to the coupling is marginal, leading to a figure-of-merit of -154.8 dBc/Hz. These results are consistent with the noiseless feature of this coupling and are comparable to those of the best state-of-the-art RC-oscillators, in the GHz range, but with the lowest power consumption (about 9 mW). The results for the three oscillators show that the amplitude- and the quadrature-errors are proportional to the component mismatches and inversely proportional to the coupling strength. Thus, increasing the coupling strength decreases both the amplitude- and quadrature-errors. With proper coupling strength, a quadrature error below 1° and amplitude imbalance below 1% are obtained. Furthermore, the simulations show that increasing the coupling strength reduces the phase noise. Hence, there is no trade-off between phase noise and quadrature error. In the twointegrator oscillator study, it was found that the quadrature error can be eliminated by adjusting the transconductances to compensate the capacitance mismatch. However, to obtain outputs in perfect quadrature one must allow some amplitude error.

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

Titanium oxide adhesion layer for high temperature annealed Si/Si3N4/TiOx/Pt/LiCoO2 battery structures

This work describes the influence of a high annealing temperature of about 700C on the Si(substrate)/Si3N4/TiOx/Pt/LiCoO2 multilayer system for the fabrication of all-solid-state lithium ion thin film microbatteries. Such microbatteries typically utilize lithium cobalt oxide (LiCoO2) as cathode material with a platinum (Pt) current collector. Silicon nitride (Si3N4) is used to act as a barrier against Li diffusion into the substrate. For a good adherence between Si3N4 and Pt, commonly titanium (Ti) is used as intermediate layer. However, to achieve crystalline LiCoO2 the multilayer system has to be annealed at high temperature. This post-treatment initiates Ti diffusion into the Pt-collector and an oxidation to TiOx, leading to volume expansion and adhesion failures. To solve this adhesion problem, we introduce titanium oxide (TiOx) as an adhesion layer, avoiding the diffusion during the annealing process. LiCoO2, Pt and Si3N4 layers were deposited by magnetron sputtering and the TiOx layer by thermal oxidation of Ti layers deposited by e-beam technique. Asdeposited and annealed multilayer systems using various TiOx layer thicknesses were studied by scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS). The results revealed that an annealing process at temperature of 700C leads to different interactions of Ti atoms between the layers, for various TiOx layer thicknesses (25–45 nm).

MEDICIÓN DE UN BRAZO DE PALANCA Y CÁLCULO DE LA INCERTIDUMBRE

En este trabajo se detalla el procedimiento de calibración del brazo de palanca de un freno de ensayo de motores eléctricos, el cual constituye la parte inicial de un proceso de calibración más amplio consistente en verificaciones adicionales de celdas de carga y medidores de velocidad. Dicho procedimiento se desarrolló y ejecutó íntegramente en el laboratorio del CIDEME (Centro de Investigación, Desarrollo y Ensayo de Máquinas Eléc-tricas), que está en proceso de implementación de las normas de calidad IRAM 301/ISO 17025. Consistió básicamente en 1) el diseño y la construcción de un calibre ajustado a las características del freno, 2) la medición y verificación de dicho instrumento, 3) su montaje en el freno y el marcado de la longitud del brazo de palanca, y 4) la obtención de la incertidumbre de la medición. La tarea se llevó a cabo con éxito, ya que permitió obtener valores acordes a los estándares del laboratorio y ganar experiencia para extender el procedimiento a los otros frenos de menor potencia disponibles.

MEDICIÓN DE UN BRAZO DE PALANCA Y CÁLCULO DE LA INCERTIDUMBRE

En este trabajo se detalla el procedimiento de calibración del brazo de palanca de un freno de ensayo de motores eléctricos, el cual constituye la parte inicial de un proceso de calibración más amplio consistente en verificaciones adicionales de celdas de carga y medidores de velocidad. Dicho procedimiento se desarrolló y ejecutó íntegramente en el laboratorio del CIDEME (Centro de Investigación, Desarrollo y Ensayo de Máquinas Eléc-tricas), que está en proceso de implementación de las normas de calidad IRAM 301/ISO 17025. Consistió básicamente en 1) el diseño y la construcción de un calibre ajustado a las características del freno, 2) la medición y verificación de dicho instrumento, 3) su montaje en el freno y el marcado de la longitud del brazo de palanca, y 4) la obtención de la incertidumbre de la medición. La tarea se llevó a cabo con éxito, ya que permitió obtener valores acordes a los estándares del laboratorio y ganar experiencia para extender el procedimiento a los otros frenos de menor potencia disponibles.

Do Archaea and bacteria co-infection have a role in the pathogenesis of chronic chagasic cardiopathy?

Chronic cardiopathy (CC) in Chagas disease is a fibrotic myocarditis with C5b-9 complement deposition. Mycoplasma and Chlamydia may interfere with the complement response. Proteolytic enzymes and archaeal genes that have been described in Trypanosoma cruzi may increase its virulence. Here we tested the hypothesis that different ratios of Mycoplasma, Chlamydia and archaeal organisms, which are frequent symbionts, may be associated with chagasic clinical forms. MATERIALS AND METHODS: eight indeterminate form (IF) and 20 CC chagasic endomyocardial biopsies were submitted to in situ hybridization, electron and immunoelectron microscopy and PCR techniques for detection of Mycoplasma pneumoniae (MP), Chlamydia pneumoniae(CP), C5b-9 and archaeal-like bodies. RESULTS: MP and CP-DNA were always present at lower levels in CC than in IF (p < 0.001) and were correlated with each other only in CC. Electron microscopy revealed Mycoplasma, Chlamydia and two types of archaeal-like bodies. One had electron dense lipid content (EDL) and was mainly present in IF. The other had electron lucent content (ELC) and was mainly present in CC. In this group, ELC correlated negatively with the other microbes and EDL and positively with C5b-9. The CC group was positive for Archaea and T. cruzi DNA. In conclusion, different amounts of Mycoplasma, Chlamydia and archaeal organisms may be implicated in complement activation and may have a role in Chagas disease outcome.