L'utilisation des ondes électromagnétiques, en tant que moyen de transmission d'informations entre les terminaux mobiles, a rapidement conduit à une congestion du spectre fréquentiel. Pour améliorer le flux de données entre utilisateurs, les autorités réglementent l'accès aux bandes de fréquences en imposant des normes strictes aux télécommunications mobiles. Ainsi, et afin d'accroître leurs capacités d'échange de données, les prochaines générations de terminaux mobiles doivent utiliser dynamiquement les ressources spectrales. Ces contraintes affectent la conception des émetteurs-récepteurs mobiles. Ils doivent transmettre des débits de données élevés en utilisant plusieurs porteuses ayant différentes modulations, tout en consommant le moins d'énergie possible, afin d'économiser l’autonomie de leurs batteries. L'émetteur Walsh tente de répondre à ces défis / The use of electromagnetic waves, as a medium for transmitting information between the mobile terminals, has quickly lead to a congestion of the frequency spectrum. To improve the data traffic flow between users, the authorities regulate the access to the frequency bands by imposing stringent standards to the mobile telecommunication. Thus, and in order to increase their data exchange capabilities, the next generations of mobile terminals have to dynamically use the spectral resources. These constraints affect the design of mobile transceivers. They must transmit high data rates by using multiple carriers and various modulation schemes, while consuming as less energy as possible, in order to save their battery life. The Walsh transmitter tries to answer these challenges.

Neste trabalho é apresentado o desenvolvimento de instrumentação eletrônica para controle e automação de um sistema de crescimento de semicondutores por Epitaxia por Feixes Moleculares. Envolve uma variedade de circuitos analógicos e digitais como: um módulo de aquisição de dados e controle baseado em uma UCP Z-80, contendo algumas interfaces digitais e analógicas multiplexadas, e comunicando-se com um microcomputador através de uma interface serial. Envolve ainda o desenvolvimento de controladores de temperatura analógicos tipo P.I.D., atuação por motores de passo e circuitos de condicionamento de sinal. / In this work is presented the development of electronic instrumentation for automation and control of a Molecular Beam Epitaxy semiconductor growth system. A variety of analog and digital instrumentation circuits have been designed and implemented, including a data acquisition and control system based on a Z-80 CPU, which controls some multiplexed digital and analog interfaces and talks to a microcomputer using serial communication. Other circuits have been also developed, including analog temperature controllers, stepper motor actuators and circuits for signal conditioning.

Neste trabalho é apresentado o desenvolvimento de instrumentação eletrônica para controle e automação de um sistema de crescimento de semicondutores por Epitaxia por Feixes Moleculares. Envolve uma variedade de circuitos analógicos e digitais como: um módulo de aquisição de dados e controle baseado em uma UCP Z-80, contendo algumas interfaces digitais e analógicas multiplexadas, e comunicando-se com um microcomputador através de uma interface serial. Envolve ainda o desenvolvimento de controladores de temperatura analógicos tipo P.I.D., atuação por motores de passo e circuitos de condicionamento de sinal. / In this work is presented the development of electronic instrumentation for automation and control of a Molecular Beam Epitaxy semiconductor growth system. A variety of analog and digital instrumentation circuits have been designed and implemented, including a data acquisition and control system based on a Z-80 CPU, which controls some multiplexed digital and analog interfaces and talks to a microcomputer using serial communication. Other circuits have been also developed, including analog temperature controllers, stepper motor actuators and circuits for signal conditioning.

This thesis presents the design of a mixed-signal CMOS multiplier implemented with short-channel PMOS transistors. The multiplier presented here forms the product of a differential input voltage and a five-bit digital code. A TSMC 0.18 µm MOSFET model is used to simulate the circuit in Cadence Design Systems. The research presented in this thesis reveals a configuration that allows the multiplier to run at a speed of 8.2 GHz with end-point nonlinearity less than 5%. The high speed and low nonlinearity make this circuit ideal for applications such as filtering and digital to analog conversion.