Durante este trabalho foram produzidas amostras vítreas (na forma bulk) de composição Bi2O3-GeO2. Na primeira parte do trabalho foram analisadas condições de preparo. Para analisar a influência do cadinho foram usados cadinhos de alumina (Al2O3) e aluminosilicato (Al2O3 - SiO2) mantendo-se fixas as concentrações de Bi2O3 e temperatura de fusão. Para analisar o efeito da temperatura de fusão foram usadas temperaturas de 1100°C e 1200°C mantendo fixa a concentração de Bi2O3 e o tipo de cadinho. Por último para analisar o efeito da concentração de Bi2O3 foram usadas amostras com diferentes concentrações de 32 %, 42% e 62% (% em peso) mantendo a temperatura de fusão. A segunda parte do trabalho consistiu em analisar a transferência de energia entre os centros de luminescentes Bi+ e os íons de túlio (Tm3+) adicionando 2 % de óxido de túlio (Tm2O3) na composição dos vidros Bi2O3-GeO2, a fim de comparar com resultados da amostra sem o referido dopante. Posteriormente foi adicionada a concentração de 0,05 % de AgNO3 para aumentar a intensidade luminescente da emissão de Tm3+ segundo a teoria do efeito plasmonico, assim como o ganho em 1470 nm. Foi montado posteriormente arranjo para medir o ganho relativo das amostras na forma bulk Bi2O3-GeO2 dopadas com Tm3+, com e sem prata, para justificar a aplicação destes vidros como materiais para uso em dispositivos amplificadores na área de telecomunicação; o uso das amostras na forma de bulk é menos dispendioso do que a fabricação dos dispositivos, e nos permite avaliar o potencial do material previamente. Foram feitas medidas de emissão para comprovar as propriedades fotoluminescentes do material, e medidas de absorção para comprovar a presença de íons de bismuto, plasmon da prata, e incorporação dos íons de Tm3+; as medidas de MET (Microscópio Eletrônico de Transmissão) foram feitas para verificar o tamanho médio das nanopartículas de prata e difração de elétrons para identificar a estrutura cristalina das nanopartículas, comprovando assim a presença da prata nos vidros. Na presença da prata o ganho aumentou em 500% atingindo 4,5 dB/cm. Os resultados que serão reportados mostram o potencial de vidros de composição Bi2O3 - GeO2 com nanopartículas de prata e Tm3+ para aplicações que requeiram luminescência intensa de banda larga na região de 1300 - 1600 nm e amplificação óptica em 1470 nm. / During this work, we produced glass samples (in bulk form) with Bi2O3-GeO2 composition. In the first part of the work, we analyzed the preparation conditions. In order to evaluate the influence of the crucible we used alumina (Al2O3) and aluminosilicate (Al2O3 - SiO2) crucibles, keeping the concentration of Bi2O3 and melting temperature fixed. To analyze the melt temperature we used the temperature of 1100 °C and 1200 °C keeping the concentration of Bi2O3 and type of crucible fixed. Finally, to analyze the effect of the concentration samples we used different concentrations of 32%, 42% and 62% (in % wt) and the melting temperature and the crucible type remained fixed. The second part of the work consisted in evaluating the energy transfer between the Bi+ luminescent centers and the Tm3+ ions by adding 2% of Tm2O3 in the composition of the Bi2O3 - GeO2 glasses, in order to compare the results with those without the rare earth ions. Subsequently, 0.05 wt % of AgNO3 was added to increase the luminescent intensity of thulium ions (Tm3+) according to the theory of the plasmonic effect as well as the gain at 1470 nm. It was later assembled an arrangement to measure the relative gain of bulk samples Bi2O3 - GeO2 doped with thulium oxide (Tm2O3), with and without silver nanoparticles, to justify the application of these glasses as materials to be used in amplifying devices; the use of bulk sample is less expensive than the fabrication of devices and allows us to evaluate previously the material potential. We carried out emission measurements to verify the photoluminescent properties of the material and absorption measurements to verify the concentration of bismuth ions, the silver plasmonic effect, and the incorporation of Tm3+ ions. TEM (Transmission Electron Microscope) was used to verify the average size of silver nanoparticles and electron diffraction to identify the crystalline structure of the nanoparticles and to prove mainly the presence of silver in the glasses. Enhancement of about 500% was observed for the relative gain that reached 4.5 dB/cm. The reported results show the potential of Bi2O3 - GeO2 composite glasses with silver nanoparticles and Tm3+ for applications requiring intense large bandwidth luminescence in the 1300-1600 nm region and optical amplification at 1470 nm.

"Hydroxyl ions are a common contaminant in optical fibers, and are responsible for strong absorption centered at 1380 nm that becomes significant over long optical path lengths. Recently, however, special fabrication methods have been developed that minimize the hydroxyl ion contamination, permitting use of the entire 1300-1700 nm spectral region for telecommunications. There is therefore interest in examining the Nd 4F3/2 to 4I13/2 transition for a potential optical amplifier at 1400 nm. In this thesis, the excited state absorption cross section and the overall gain/loss spectrum of neodymium in a silica glass fiber were determined for the 1200-1500 nm wavelength region using the pump-probe method. The ground state absorption cross section was also determined from transmission measurements, and the stimulated emission cross section was calculated using the fluorescence spectrum and the McCumber relation. Oscillator strengths for absorption and emission transitions were calculated in the 800-1600 nm wavelength range using the Judd-Ofelt method. The above procedures were followed for both the Nd-doped fiber, as well as an erbium-doped silica fiber. The shape of the Nd emission spectrum is also noteworthy, since the characteristic Nd peak at 1064 nm is not observed, although there is strong emission at 1092 nm. The pump-probe measurements revealed significant excited state absorption loss between 1200 and 1350 nm, due to excitation from the 4F3/2 to the higher 4G9/2 and 4G7/2 states. Between 1350 and 1475 nm, there was no net gain or loss that could be observed beyond the level of the noise. For the glass fibers studied, it appears that in the spectral region of interest for an optical amplifier, the stimulated emission and excited state absorption cancel one another out."

Durante este trabalho foram produzidas amostras vítreas (na forma bulk) de composição Bi2O3-GeO2. Na primeira parte do trabalho foram analisadas condições de preparo. Para analisar a influência do cadinho foram usados cadinhos de alumina (Al2O3) e aluminosilicato (Al2O3 - SiO2) mantendo-se fixas as concentrações de Bi2O3 e temperatura de fusão. Para analisar o efeito da temperatura de fusão foram usadas temperaturas de 1100°C e 1200°C mantendo fixa a concentração de Bi2O3 e o tipo de cadinho. Por último para analisar o efeito da concentração de Bi2O3 foram usadas amostras com diferentes concentrações de 32 %, 42% e 62% (% em peso) mantendo a temperatura de fusão. A segunda parte do trabalho consistiu em analisar a transferência de energia entre os centros de luminescentes Bi+ e os íons de túlio (Tm3+) adicionando 2 % de óxido de túlio (Tm2O3) na composição dos vidros Bi2O3-GeO2, a fim de comparar com resultados da amostra sem o referido dopante. Posteriormente foi adicionada a concentração de 0,05 % de AgNO3 para aumentar a intensidade luminescente da emissão de Tm3+ segundo a teoria do efeito plasmonico, assim como o ganho em 1470 nm. Foi montado posteriormente arranjo para medir o ganho relativo das amostras na forma bulk Bi2O3-GeO2 dopadas com Tm3+, com e sem prata, para justificar a aplicação destes vidros como materiais para uso em dispositivos amplificadores na área de telecomunicação; o uso das amostras na forma de bulk é menos dispendioso do que a fabricação dos dispositivos, e nos permite avaliar o potencial do material previamente. Foram feitas medidas de emissão para comprovar as propriedades fotoluminescentes do material, e medidas de absorção para comprovar a presença de íons de bismuto, plasmon da prata, e incorporação dos íons de Tm3+; as medidas de MET (Microscópio Eletrônico de Transmissão) foram feitas para verificar o tamanho médio das nanopartículas de prata e difração de elétrons para identificar a estrutura cristalina das nanopartículas, comprovando assim a presença da prata nos vidros. Na presença da prata o ganho aumentou em 500% atingindo 4,5 dB/cm. Os resultados que serão reportados mostram o potencial de vidros de composição Bi2O3 - GeO2 com nanopartículas de prata e Tm3+ para aplicações que requeiram luminescência intensa de banda larga na região de 1300 - 1600 nm e amplificação óptica em 1470 nm. / During this work, we produced glass samples (in bulk form) with Bi2O3-GeO2 composition. In the first part of the work, we analyzed the preparation conditions. In order to evaluate the influence of the crucible we used alumina (Al2O3) and aluminosilicate (Al2O3 - SiO2) crucibles, keeping the concentration of Bi2O3 and melting temperature fixed. To analyze the melt temperature we used the temperature of 1100 °C and 1200 °C keeping the concentration of Bi2O3 and type of crucible fixed. Finally, to analyze the effect of the concentration samples we used different concentrations of 32%, 42% and 62% (in % wt) and the melting temperature and the crucible type remained fixed. The second part of the work consisted in evaluating the energy transfer between the Bi+ luminescent centers and the Tm3+ ions by adding 2% of Tm2O3 in the composition of the Bi2O3 - GeO2 glasses, in order to compare the results with those without the rare earth ions. Subsequently, 0.05 wt % of AgNO3 was added to increase the luminescent intensity of thulium ions (Tm3+) according to the theory of the plasmonic effect as well as the gain at 1470 nm. It was later assembled an arrangement to measure the relative gain of bulk samples Bi2O3 - GeO2 doped with thulium oxide (Tm2O3), with and without silver nanoparticles, to justify the application of these glasses as materials to be used in amplifying devices; the use of bulk sample is less expensive than the fabrication of devices and allows us to evaluate previously the material potential. We carried out emission measurements to verify the photoluminescent properties of the material and absorption measurements to verify the concentration of bismuth ions, the silver plasmonic effect, and the incorporation of Tm3+ ions. TEM (Transmission Electron Microscope) was used to verify the average size of silver nanoparticles and electron diffraction to identify the crystalline structure of the nanoparticles and to prove mainly the presence of silver in the glasses. Enhancement of about 500% was observed for the relative gain that reached 4.5 dB/cm. The reported results show the potential of Bi2O3 - GeO2 composite glasses with silver nanoparticles and Tm3+ for applications requiring intense large bandwidth luminescence in the 1300-1600 nm region and optical amplification at 1470 nm.

Esta dissertação apresenta o projeto de um amplificador de baixo ruído (LNA) para aplicação em 2,4 GHz na tecnologia CMOS 0,35 µm. A metodologia baseia-se na obtenção das dimensões dos dispositivos do circuito considerando o consumo de potência e o desempenho em relação ao ruído. Os resultados mostram que a metodologia implementada é eficaz no projeto de um LNA quando se comparam os resultados obtidos nos cálculos com os resultados obtidos no simulador. A expressão de corrente que considera canal curto impõe maior precisão nos resultados, pois se aplica o ajuste de curva com a curva de corrente obtida pelo simulador. Isto permite maior precisão nos resultados dos cálculos de ruído. O fluxo do projeto baseia-se na implementação de dispositivos ideais obtidos de projeto com o propósito de fazer-se comparações dos resultados de cálculos com as simulações, então, usa-se dispositivos reais e ajusta-se o circuito para encontrar melhores desempenhos quanto às especificações. Os resultados mostram a necessidade de ajuste do circuito quando inserido o modelo do indutor para que se consiga desempenhos próximos dos obtidos inicialmente. Em seguida, realiza-se o layout do circuito e sua extração parasitária para fins de fabricação. Verifica-se que a metodologia apresentada é capaz de direcionar a um projeto de um LNA na tecnologia com resultados finais satisfatórios de ganho, ruído e consumo. Assim os resultados esperados são 14,66 dB de ganho, 1,9 dB de fator de ruído e 2,99 mA de consumo de corrente (9,87 mW em 3,3 V de alimentação) ambos no primeiro estágio. / This work presents the design of a low-noise amplifier (LNA) for application at 2.4 GHz using CMOS 0.35 µm technology. The methodology is based on obtaining the dimensions of the devices taking into account of power consumption and performance on noise. Results show that the implemented methodology is efficient in the design of LNAs when it compares results obtained by calculation and simulation. The expression of current that considers short-channel effects increases the precision of results because curve fitting is applied with the current of the simulator. This permits precision on the results of the noise calculation. The design-flow firstly bases on implementation of ideal devices obtained by design on purposes of doing comparisons between calculated and simulated results, then real devices is used and the circuit is fixed to find better performance regarding the specifications. The results showed the necessity of adjusts in the circuit when the inductor is inserted to reach a closer initial performance. Afterwards, the layout of the circuit and its parasitic extraction are worked out for purposes of fabrication. It is verified that this methodology is capable of directing to the design of LNAs using the proposed technology with satisfactory final results of gain, noise and power consumption. Therefore, the expected results are 14,66 dB of gain, 1,9 dB of noise figure, 2,99 mA of current consumption (9,87 mW within 3.3 V of supply voltage) both of them at first stage.

abstract: There is an ever-increasing demand for higher bandwidth and data rate ensuing from exploding number of radio frequency integrated systems and devices. As stated in the Shannon-Hartley theorem, the maximum achievable data rate of a communication channel is linearly proportional to the system bandwidth. This is the main driving force behind pushing wireless systems towards millimeter-wave frequency range, where larger bandwidth is available at a higher carrier frequency. Observing the Moor’s law, highly scaled complementary metal–oxide–semiconductor (CMOS) technologies provide fast transistors with a high unity power gain frequency which enables operating at millimeter-wave frequency range. CMOS is the compelling choice for digital and signal processing modules which concurrently offers high computation speed, low power consumption, and mass integration at a high manufacturing yield. One of the main shortcomings of the sub-micron CMOS technologies is the low breakdown voltage of the transistors that limits the dynamic range of the radio frequency (RF) power blocks, especially with the power amplifiers. Low voltage swing restricts the achievable output power which translates into low signal to noise ratio and degraded linearity. Extensive research has been done on proposing new design and IC fabrication techniques with the goal of generating higher output power in CMOS technology. The prominent drawbacks of these solutions are an increased die area, higher cost per design, and lower overall efficiency due to lossy passive components. In this dissertation, CMOS compatible metal–semiconductor field-effect transistor (MESFETs) are utilized to put forward a new solution to enhance the power amplifier’s breakdown voltage, gain and maximum output power. Requiring no change to the conventional CMOS process flow, this low cost approach allows direct incorporation of high voltage power MESFETs into silicon. High voltage MESFETs were employed in a cascode structure to push the amplifier’s cutoff frequency and unity power gain frequency to the 5G and K-band frequency range. This dissertation begins with CMOS compatible MESFET modeling and fabrication steps, and culminates in the discussion of amplifier design and optimization methodology, parasitic de-embedding steps, simulation and measurement results, and high resistivity RF substrate characterization. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2019

Due to the rapid development of telecommunication devices, operating speeds are getting faster and more power is being consumed by those devices. Therefore, there is a big concern on how to prolong the battery life in order to fit consumers’ needs. Power amplifiers (PA) at the front end of wireless equipment have drawn a big concern from engineers because of their large power consumption in the system. There is a lot research conducted on PA solutions for improving power-added efficiency (PAE) of amplifiers. PAE is a figure of merit representing how efficient the PA converts DC power to RF power. With PAE increased, the device is able to output the same amount of power with less DC power consumed. Non-linear Class-F and Class-F-1 PAs have drawn the most attention among all different classes of PAs from engineers because of their capability of outputting high power and providing good PAE. Class-F boosts up PAE by controlling the harmonic content at the output. Advanced Design System (ADS) from Agilent is used for design and simulation based on the ADS model of Cree’s CGH40010 high electron mobility transistor (HEMT). A high efficiency power amplifier is fabricated on RT/duroid 5870 high frequency laminate board. In this design, the harmonics at the input are controlled as well as the harmonics at the output. An input wave-shaping network is designed to shape the waveforms at the gate. In this case, the PAE is boosted 30% higher than the PA with only the output wave-shaping network. By terminating harmonics with proper impedances at the output, a square voltage waveform and a half-sine current waveform are obtained at the transistor drain terminal. The overlapping area between the voltage and current waveforms can be reduced as well as the active device power consumption. The final design operating at 1GHz produced a PAE of 89% with 38.35dBm output power in simulation and PAE of 78% with 38.7dBm output power as the result of the IEEE PA design contest. The thesis has shown the effectiveness of the Class-F PA to boost up PAE by preventing the 2nd and 3rd harmonic power from delivering to the load and shaping the waveforms at the transistor terminals. It also shows the benefit of using radial stubs in wave-shaping networks over open-circuit stubs.

This thesis presents a study and implementation of several measurement procedures used to efficiently generate non-linear measurement-based behavioral models primary for microwave amplifiers. Behavioral models are a solution for representing devices that can present linear and/or non-linear behavior when little or no information about the internal structure is known. Measurement-based behavioral models are an advantage since they can be extracted from a direct measurement of the device. This work addresses some of the challenges of these types of measurements. A set of software modules has been produced that combine several modern techniques to efficiently generate practical models using equipment commonly available in a typical microwave lab. Advanced models using new and more complex equipment are also discussed. Modeling of the non-linear operation of power amplifiers is a common subject of study since it provides a path to improved system simulations. However, the measurement process used for non-linear behavioral modeling of PAs requires either non-linear measurement instrumentation, not yet widely available, or numerous measurements that makes the process tedious and susceptible to errors. Power dependent S-Parameters obtained with a conventional Vector Network Analyzers (VNA) can be used to extract AM-to-AM and AM-to-PM behavior of a device and to generate, simple but useful, behavioral models. A careful analysis of the characteristics of common RF measurement instrumentation combined with knowledge of common non-linear phenomena provides with the conditions under which useful models can be generated. The results of this work are presented as several programs implemented in National Instruments LabVIEW that will sequence through the different measurements required for the generation of measurement-based behavioral models. The implemented models are known as P2D and S2D models available with Agilent Advanced Design System (ADS.) The code will communicate with the measurement instrumentation and decide on the most efficient way to extract the data. Once the data is extracted, the code will put into the appropriate syntaxes required by the model for direct and convenient setup of the generated models in ADS.

<p>This master's thesis addresses two main problems. The first is how to suppress a common mode voltage that appears for current shunts, and the second how to let a voltage divider work under an unloaded condition to prevent loading errors and thereby a decreased measurement accuracy. Both these problems occurs during calibration of power meters, and verification of current shunts and voltage dividers. To the first problem three alternative solutions are presented; prototype a proposed instrumentation amplifier circuit, evaluate the commercial available instrumentation amplifier Analog Devices AD8130 or let the voltage measuring device suppress the common mode voltage. It is up to the researchers at SP to choose a solution. To address the second problem, a prototype buffer amplifier is built and verified. Measurements of the buffer amplifier show that it performs very well. At 100 kHz, the amplitude error is less than 20 μV/V, the phase error is less than 20 μrad, and the input R_p is over 10 MΩ. This is performance in line with the required to make accurate measurements possible at 100 kHz and over that.</p>

<p>In this thesis, a new way of using predisortion for linearization of power amplifiers is evaluated. In order to achieve an adequate power level for the jamming signal, power amplifiers are used in military jamming systems. Due to the nonlinear characteristic of the power amplifier, distortion will be present at the output. As a consequence, unwanted frequencies are subject to jamming. To decrease the distortion, linearization of the power amplifier is necessary. </p><p>In the system of interest, a portion of the distorted power amplifier output signal is fed back. Using this measurement, a predistortion signal is synthesized to allow suppression of the unwanted frequency components. The predistortion signal is updated a number of times in order to achieve a good outcome. Simulations are carried out in Matlab for testing of the algorithm. </p><p>The evaluation of the new linearization technique shows promising results and that good suppression of distortion components is achieved. Furthermore, new predistortion features are possible to implement, such as predistorsion in selected frequency bands. However, real hardware testing needs to be carried out to confirm the results.</p>

<p>In this master degree work, a digital attenuator and a low noise amplifier (LNA) have been designed and integrated with the RF front-end receiver for IEEE 802.11b Wireless LAN standard. Firstly, the 4-bit digitally controlled attenuator has been designed with theattenuation range of 50 to 80 dB and reflection coefficient less than -25 dB. Next, the single stage wide band low noise amplifier with voltage gain larger than 14 dB and noise figure below 4 dB has been designed to operate at frequency 2.4 GHz. Finally, the integration with a down-conversion mixer has been done and evaluated its performance.</p><p>The attenuator and low noise amplifier desired in this thesis have been implemented using standard CMOS 0.35µm technology and validated by the simulation tools Cadence Spectre-RF.</p>