Dissertations / Theses on the topic 'Transistor amplifier in C class'

This master‘s thesis deals with analysis of electronic dynamical systems exhibiting chaotic solution. In introduction, some basic concepts for better understanding of dynamical systems are explained. After introduction, current knowledge from the world of circuits exhibiting chaotic solutions are discussed. The best-known chaotic systems are analyzed numerically in Matlab software. Numerical analysis and experimental verification were demonstrated at C class transistor amplifier, which confirmed the chaotic behavior and generation of a strange attractor.

Ce travail répond à un besoin industriel accru en termes d’amplification des signaux sur porteuses à enveloppes variables utilisés par les systèmes de télécommunications actuels. Ces signaux disposent d’un fort PAPR et d’une distribution statistique d’enveloppe centrée en-deçà de la valeur crête d’enveloppe. La raison pour laquelle les industriels télécoms requièrent alors des amplificateurs de très fortes puissances de sortie, robustes, fiables et ayant une dépense énergétique optimale le long de la dynamique d’enveloppe associée à un niveau de linéarité acceptable. Ce document expose les résultats d’étude et de réalisation de deux Amplificateurs de Puissance Doherty (APD) à haut rendement encapsulés en boîtiers plastiques QFN. Le premier est un amplificateur Doherty symétrique classique (APD-SE) et le second est un amplificateur à deux entrées RF (APD-DE). Ces démonstrateurs fonctionnant en bande C sont fondés sur l’utilisation de la technologie Quasi-MMIC associant des barrettes de puissance à base des transistors HEMTs AlGaN/GaN sur SiC à des circuits d’adaptation en technologie ULRC. L’approche Quasi-MMIC associée à la solution d’encapsulation plastique QFN permettant une meilleure gestion des comportements thermiques offre des performances électriques similaires à celles de la technologie MMIC avec des coûts et des cycles de fabrication très attractifs. Durant ces travaux, une nouvelle méthode d’évaluation des transistors dédiés à la conception d’amplificateurs Doherty a été développée et mise en oeuvre. L’utilisation intensive des simulations électromagnétiques 2.5D et 3D a permis de bien prendre en compte les effets de couplages entre les différents circuits dans l’environnement du boîtier QFN. Les résultats des tests des amplificateurs réalisés fonctionnant sur une bande de 1GHz ont permis de valider la méthode de conception et ont montré que les concepts avancés associés à l’approche Quasi-MMIC ainsi qu’à des technologies d’encapsulation plastique, peuvent générer des fonctions micro-ondes innovantes. Les caractérisations de l’APD-DE ont relevé l’intérêt inhérent à la préformation des signaux d’excitation et des points de polarisation de chaque étage de l’amplificateur
This work responds to an increased industrial need for on carrier signals with variable envelope amplification used by current telecommunications systems. These signals have a strong PAPR and an envelope statistical distribution centred below the envelope peak value, the reason why the telecom industrialists then require a robust and reliable high power amplifiers having an energy expenditure along of the envelope dynamics associated with an acceptable level of linearity. This document presents the results of the study and realization of two, high efficiency, Doherty Power Amplifiers (DPA) encapsulated in QFN plastic packages. The first is a conventional Doherty power Amplifier (DPA-SE) and the second is a dual-input Doherty power amplifier (DPA-DE). These C-band demonstrators are based on the use of Quasi-MMIC technology combining power bars based on the AlGaN/GaN transistors on SiC to matching circuits in ULRC technology. The Quasi-MMIC approach combined with Quasi-MMIC approach combined with QFN plastic package solution for better thermal behaviour management offers electrical performances similar to those of MMIC technology with very attractive coasts and manufacturing cycles. During this work, a new evaluation method for the transistors dedicated to the design of DPA was developed and implemented. The intensive use of 2.5D and 3D electromagnetic simulations made it possible to take into account the coupling effects existing between the different circuits in the QFN package environment. The results of the tests of the amplifiers realised and operating on 1GHz bandwidth validated the design method and showed that the advanced concepts associated with the Quasi-MMIC approach as well as plastic encapsulation technologies can generate innovative microwave functions. The characterizations of the DPA-DE have noted the interest inherent in the preformation of the excitation signals and the bias points of each stage of the amplifier

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This work integrates a harmonic tuning mechanism in synergy with the GaN HEMT transistor for 5G mobile transceiver applications. Following a theoretical study on the operational behavior of the Class-F power amplifier (PA), a complete amplifier design procedure is described that includes the proposed Harmonic Control Circuits for the second and third harmonics and optimum loading conditions for phase shifting of the drain current and voltage waveforms. The performance improvement provided by the Class-F configuration is validated by comparing the experimental and simulated results. The designed 10W Class-F PA prototype provides a measured peak drain efficiency of 64.7% at 1dB compression point of the PA at 3.6GHz frequency.

Class C power amplifiers offer higher efficiency than class B power amplifiers, but suffer from poor linearity. A feedback based biasing system to improve the linearity of a class C power amplifier is designed. A class B amplifier with a gain of 20 dB and 20 MHz bandwidth at 900 MHz acts as the launching point for the design. The biasing and output network of the class B power amplifier is modified to produce a class C amplifier at conduction angles of 180°, 162°, 126°, 90°, and 54°. A feedback based biasing system, which uses two matched and scaled down transistors, compares the DC current of a class B and a class C biased transistor. This comparison is used to control the biasing voltage of the amplifier. The performance for each class C amplifier is simulated with the proposed constant conduction angle biasing (CCAB) system. The conduction angle, transducer gain, operational gain, VSWR, and drain efficiency are measured from simulation for each of the 5 normally biased and 5 CCAB amplifiers. Dynamic ranges of over 8 dB are demonstrated for the CCAB amplifiers. The effects of loop gain, temperature, and operating frequency for the 126° amplifier are simulated. The 3rd order intermodulation products of a 10 MHz AM modulated 900 MHz signal are compared for the 126° normally biased and CCAB biased amplifier as well as the class B amplifier. The difference between the fundamental and the 3rd order intermodulation products is shown to improve from 9.9 dB for the normal class C to 28.7 dB for the CCAB amplifier.

In today´s digital world, information and communication technology accounts for 3% and 2% of the global power consumption and CO2 emissions respectively. This alarming figure is on an upward trend, as future telecommunications systems and handsets will become even more power hungry since new services with higher bandwidth requirements emerge as part of the so called ¿future internet¿ paradigm. In addition, the mobile handset industry is tightly coupled to the consumer need for more sophisticated handsets with greater battery lifetime. If we cannot make any significant step to reducing the energy gap between the power hungry requirements of future handsets, and what battery technology can deliver, then market penetration for 4G handsets can be at risk. Therefore, energy conservation must be a design objective at the forefront of any system design from the network layer, to the physical and the microelectronic counterparts. In fact, the energy distribution of a handset device is dominated by the energy consumption of the RF hardware, and in particular the power amplifier design. Power amplifier design is a traditional topic that addresses the design challenge of how to obtain a trade-off between linearity and efficiency in order to avoid the introduction of signal distortion, whilst making best use of the available power resources for amplification. However, the present work goes beyond this by investigating a new line of amplifiers that address the green initiatives, namely green power amplifiers. This research work explores how to use the Doherty technique to promote efficiency enhancement and thus energy saving. Five different topologies of RF power amplifiers have been designed with custom-made signal splitters. The design core of the Doherty technique is based on the combination of a class B, class AB and a class C power amplifier working in synergy; which includes 90-degree 2-way power splitter at the input, quarter wavelength transformer at the output, and a new output power combiner. The frequency range for the amplifiers was designed to operate in the 3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results show that 30dBm output power can be achieved with 67% power added efficiency (PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for base stations which marks a 14% and 11% respective improvement over current stateof- the-art, while meeting the power output requirements for mobile WiMAX applications.

In today's digital world, information and communication technology accounts for 3% and 2% of the global power consumption and CO2 emissions respectively. This alarming figure is on an upward trend, as future telecommunications systems and handsets will become even more power hungry since new services with higher bandwidth requirements emerge as part of the so called 'future internet' paradigm. In addition, the mobile handset industry is tightly coupled to the consumer need for more sophisticated handsets with greater battery lifetime. If we cannot make any significant step to reducing the energy gap between the power hungry requirements of future handsets, and what battery technology can deliver, then market penetration for 4G handsets can be at risk. Therefore, energy conservation must be a design objective at the forefront of any system design from the network layer, to the physical and the microelectronic counterparts. In fact, the energy distribution of a handset device is dominated by the energy consumption of the RF hardware, and in particular the power amplifier design. Power amplifier design is a traditional topic that addresses the design challenge of how to obtain a trade-off between linearity and efficiency in order to avoid the introduction of signal distortion, whilst making best use of the available power resources for amplification. However, the present work goes beyond this by investigating a new line of amplifiers that address the green initiatives, namely green power amplifiers. This research work explores how to use the Doherty technique to promote efficiency enhancement and thus energy saving. Five different topologies of RF power amplifiers have been designed with custom-made signal splitters. The design core of the Doherty technique is based on the combination of a class B, class AB and a class C power amplifier working in synergy; which includes 90-degree 2-way power splitter at the input, quarter wavelength transformer at the output, and a new output power combiner. The frequency range for the amplifiers was designed to operate in the 3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results show that 30dBm output power can be achieved with 67% power added efficiency (PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for base stations which marks a 14% and 11% respective improvement over current stateof- the-art, while meeting the power output requirements for mobile WiMAX applications.

The goal of this diploma's thesis is to create a design of a two stages amplifier working in a band reserved for the secondary surveillance radar at the frequency of 1090 MHz. Output power of the amplifier should be 20 W and efficiency should be as high as possible. Because of this the second stage is designed in class C. Contents of this diploma's thesis include a theoretical analysis, simulations of the amplifier parameters, comparison of the Ansys Designer and AWR Microwave Office simulation programs and design of both stages of the amplifier, followed by a comparison of the measured parameters with the simulations.

Ce travail concerne les transistors bipolaires à hétérogène TBH SiGe. En particulier, l'auto-échauffement des transistors unitaires et le couplage thermique avec leurs plus proches voisins périphériques sont caractérisés et modélisés. La rétroaction électrothermique intra- et inter-transistor est largement étudiée. En outre, l’impact des effets thermiques sur la performance de deux circuits analogiques est évalué. L'effet d'autoéchauffement est évalué par des mesures à basse fréquence et des mesures impulsionnelles DC et AC. L'auto-échauffement est diminué de manière significative en utilisant des petites largeurs d'impulsion. Ainsi la dépendance fréquentielle de l’autoéchauffementa été étudiée en utilisant les paramètres H et Y. De nouvelles structures de test ont été fabriqués pour mesurer l'effet de couplage. Les facteurs de couplage thermique ont été extraits à partir de mesures ainsi que par simulations thermiques 3D. Les résultats montrent que le couplage des dispositifs intra est très prononcé. Un nouvel élément du modèle de résistance thermique récursive ainsi que le modèle de couplage thermique a été inclus dans un simulateur de circuit commercial. Une simulation transitoire entièrement couplée d'un oscillateur en anneau de 218 transistors a été effectuée. Ainsi, un retard de porte record de 1.65ps est démontré. À la connaissance des auteurs, c'est le résultat le plus rapide pour une technologie bipolaire. Le rendement thermique d'un amplificateur de puissance à 60GHz réalisé avec un réseau multi-transistor ou avec un transistor à plusieurs doigts est évalué. La performance électrique du transistor multidoigt est dégradée en raison de l'effet de couplage thermique important entre les doigts de l'émetteur. Un bon accord est constaté entre les mesures et les simulations des circuits en utilisant des modèles de transistors avec le réseau de couplage thermique. Enfin, les perspectives sur l'utilisation des résultats sont données
The power generate by modern silicon germanium (SiGe) heterojunction bipolar transistors (HBTs) can produce large thermal gradients across the silicon substrate. The device opering temperature modifies model parameters and can significantly affect circuit operation. This work characterizes and models self-heating and thermal coupling in SiGe HBTs. The self-heating effect is evaluated with low frequency and pulsed measurements. A novel pulse measurement system is presented that allows isothermal DC and RF measurements with 100ns pulses. Electrothermal intra- and inter-device feedback is extensively studied and the impact on the performance of two analog circuits is evaluated. Novel test structures are designed and fabricated to measure thermal coupling between single transistors (inter-device) as well as between the emitter stripes of a multi-finger transistor (intra-device). Thermal coupling factors are extracted from measurements and from 3D thermal simulations. Thermally coupled simulations of a ring oscillator (RO) with 218 transistors and of a 60GHz power amplifier (PA) are carried out. Current mode logic (CML) ROs are designed and measured. Layout optimizations lead to record gate delay of 1.65ps. The thermal performance of a 60GHz power amplifier is compared when realized with a multi-transistor array (MTA) and with a multi-finger trasistor (MFT). Finally, perspectives of this work within a CAD based circuit design environment are discussed

The thesis describes design and construction of vibration generator driver. The device is controlled via standard Ethernet interface and allows user to change parameters of generated function in PC application which reads and evaluates frequency and amplitude from real-time measured data while the test is running. In the introduction, vibration tests and choice of generators and power amplifiers are described. Next part is focused on every aspect of the hardware design. Last two chapters implement firmware for all three microcontrollers and software for PC application.

The ever increasing diversity in communication systems has created a demand for constant improvements in receiver components. This thesis describes the design and characterisation of front-end receiver components for various challenging applications, including characterisation of low noise foundry processes, LNA design and multi-band antenna design. It also includes a new theoretical analysis of noise coupling in low noise phased array receivers.In LNA design much depends on the choice of the optimum active devices. A comprehensive survey of the performance of low noise transistors is therefore extremely beneficial. To this end a comparison of the DC, small-signal and noise behaviours of 10 state-of-the-art GaAs and InP based pHEMT and mHEMT low noise processes has been carried out. Their suitability in LNA designs has been determined, with emphasis on the SKA project. This work is part of the first known detailed investigation of this kind. Results indicate the superiority of mature GaAs-based pHEMT processes, and highlight problems associated with the studied mHEMT processes. Two of the more promising processes have then been used to design C-band and UHF-band MMIC LNAs. A new theoretical analysis of coupled noise between antenna elements of a low noise phased array receiver has been carried out. Results of the noise wave analysis, based on fundamental principles of noisy networks, suggest that the coupled noise contribution to system noise temperatures should be smaller than had previously been suggested for systems like the SKA. The principles are applicable to any phased array receiver. Finally, a multi-band antenna has been designed and fabricated for a severe operating environment, covering the three extremely crowded frequency bands, the 2.1 GHz UMTS, the 2.4 GHz ISM and the 5.8 GHz ISM bands. Measurements have demonstrated excellent performance, exceeding that of equivalent commercial antennas aimed at similar applications.

Object of the master´s thesis is design of a high voltage power supply for testing insulation materials with output voltage 50 V - 2 kV at fixed frequency 50 Hz. The power supply is controlled by personal computer and measured data are sent back to the personal computer. The Universal Serial Bus (USB) is used for communication between the PC and the device.

Power amplifiers are at the heart of any high frequency communications network. Increasing the output power of amplifiers is conventionally carried out through 90-degree hybrids at frequencies above 3GHz and through 180-degree hybrids at lower frequencies. In this thesis, we go through the design, simulation, and prototype building and testing phases of a C-band, 47dBm solid-state microwave power amplifier and investigate its performance using the two types of hybrids. The device used is a Fujitsu device consisting of two independent transistors; each has a 10dB linear gain and a saturated output power of 44dBm. Three simulation packages were used in the design phase, ADS, a product of Hewlett-Packard, Zeland, a product of Zeland Software Inc, and Sonnet b, a product of Sonnet Software Inc. The results of tests revealed that, when a 180-degree hybrid was used, the amplifier exhibited better performance in terms of output power, power-added efficiency, and inter-modulation distortion. However, the amplifier utilizing a 90-degree hybrid exhibited better return loss results. The design, simulation, and testing of the amplifier were carried out at Fujitsu FCSI under the guidance and appreciated help of the applications lab engineering team.