abstract: Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity. / Dissertation/Thesis / M.S. Electrical Engineering 2013

Made available in DSpace on 2016-03-15T19:37:37Z (GMT). No. of bitstreams: 1 FAUSTO_MIZUTANI_ENG.pdf: 975527 bytes, checksum: 1384f3ad6af75b99bf9eaa01b7a2fc3a (MD5) Previous issue date: 2006-08-29 / The performance of a distributed Raman amplifier at C and S bands using the TrueWave Reach LWP fiber in 100 km span is analyzed through numerical simulations. The physical parameters of the fiber, such as, attenuation, dispersion, and Raman gain efficiency for C and S bands were experimentally characterized by the manufacturer, the OFS Denmark. It is required around four pumping lasers to assure an on-off gain of approximately 15dB in 70nm (1500nm to 1570nm), covering operation in the C and S band. / O desempenho de uma amplificador Raman distribuído na banda C e S utilizando a fibra TrueWave Reach LWP em 100 km de enlace é analisado através de simulações numéricas. Os parâmetros físicos da fibra, como atenuação, dispersão, e eficiência de ganho Raman para bandas C e S foram caracterizados experimentalmente pelo fabricante, a OFS Denmark. Em torno de quatro lasers de bombeamento são necessários para garantir um ganho on-off da ordem de 15dB em 70nm (1500nm a 1570nm), cobrindo a operação na banda C e S.

The design and study of multiple RF direct digital manufactured (DDM) devices are presented in this work. A 2.45 GHz, 180°; hybrid coupler is designed to provide the space required for other system components. The coupler is designed and manufactured on a 32 mil Rogers 4003C substrate and adapted to a 100% in-fill acrylonitrile butadiene styrene (ABS) substrate. A size reduction of 66% is accomplished with a bandwidth of 16%. A DDM Ku band connector is modeled and fabricated using varying relative dielectric constants of 50% and 100% in-fill ABS. The connector maintains less than 0.45 dB of insertion loss up to 14 GHz and greater than 10dB of return loss up to 15 GHz. A lumped component model is also developed to model the damaged transition of the connector with agreement to numerical electromagnetic simulation software. Lastly, a thermal and RF study of a Ku band power amplifier (PA) is performed. Two 5 mil 100% in-fill ABS PA test fixtures are fabricated with a varying number of vias. The designs are biased at various operating points to collect thermal and RF data. The PA operates at 151°C before melting the ABS substrate. A thermal model is developed from the measurement data to predict the temperatures at given power levels with good agreement between simulation and model data.

Wideband amplifiers are an important part of analog design, and much effort has been expended in improving them. A popular implementation of a wideband amplifier is to use one or two stages with high gain in one or both stages. An alternative to this method is presented in this work, developed for Metal Oxide Semiconductor (MOS) amplifiers. The new approach, building on previous work in bipolar technology, uses multiple differential MOS stages to achieve similar gain requirements to other wideband amplifiers. It is shown that multiple stages with low gain, if implemented according to the present design method, can lead to better gain-bandwidth product (GBW) than a few stages. As part of the design process, GBW is optimized and current draw is reduced. Derived equations are used to find the ideal device widths of each stage to improve GBW. The amplifier's current draw is reduced through increasing the widths of each successive stage according to a derived, fixed taper factor. Simulation of the resulting amplifier shows that these optimization procedures can improve GBW by 20% or more over a nonoptimized cascaded amplifier.

This master’s thesis deals with the design and the realization of a laboratory teaching device, which includes two-port parts with nonlinear transmission characteristics corresponding to quadratic, inverse quadratic and cubic functions. It also includes a more complicated design of a polynomial function converter that offers students a practical view of functions mathematically designed while verifying their accuracy in laboratory exercises. The whole concept is supported by the design of the power supply circuit and the harmonic signal generator. The individual features of this project are feasible from components commercially available.

This work deals with comparison of individual types of electroacoustic transducers, their properties and practical use. Furthermore, design and manufacture of a magnetoplanar transducer, its integration into headphones and the production of headphone amplifier. The first chapter summarizes all types of electroacoustic transducers, their properties, advantages, disadvantages, and their use in practice. The second chapter deals with the classes of amplifiers. The third chapter deals with the choice of design of a magnetoplanar transducer, headphones, and selected type of headphone amplifier. The last chapter describes the production process of individual parts of the headphones, transducer and amplifier, including the final measurement.

The contents of this thesis is a realization of a low noise amplifier for the band from 137MHz to 138MHz and a antenna for the recieving of the signal from NOAA satellites. The proper function of the low niose amplifier is verified by Ansoft Desinger simulation and the proper function of the antenna is verified by HFSS simulation. Both devices are realizated like prototypes and their parametres are measured.

This thesis describes a design of a driver for a specific type of laser VCSEL. Models for simulation in PSpice OrCAD have been developed for this type of laser. The qualities of the designed driver aim to be equal to the integrated drivers that are available and to remove some of their drawbacks. It consists of the following components: input LVPECL receiver/driver, differential amplifier, fixed source of a modulation current, circuit of automatic power control. Regulation of the modulation current is dealt with atypically using an aptly selected input LVPECL receiver/driver which enables to control the voltage amplitude on its output by means of voltage. The thesis also describes different types of coupling between laser and driver. The most appropriate alternative is selected taking into consideration the unconventional design of the driver. The connection of the driver is supplemented by a microcontroller which secures control of output optical power by means of a serial bus RS232.

The aim of the master thesis is on lock-in amplifiers. Amplifier's basic parts and lock-in circuits description is listed in introductory chapters. The thesis offers overview of parameters of chosen devices available on the market and their possible usage. We describe HF2LI device functions and usage of ziControl software. With the aim to verify properties of the device and ziControl software, one of the last chapters focuses on manipulation with HF2LI device. The conducted experiments and achieved results are presented in the last chapter.

This master's thesis is concerned with the basis of ultra-acoustics and it explains the application of Doppler effect in medicine as a diagnostic method used for measuring blood flow velocity in blood vessels. The thesis also presents Doppler systems used for diagnostic purposes. It describes the principles of these systems, shows accompanying flowcharts and explains the function of these systems. There is also included the system design of the whole ultrasonic blood flow velocity meter. The system has been designed for the specified parameters with continuous 4 MHz operating frequency, generated intensity of ultrasound 100 mW/cm^2 and diameter D-shaped transmitting transducer 8 mm. In the design of personal solution there are described all the function blocks of the ultrasonic meter. There is also described the choice of appropriate components and designed all the required supply voltages. All the function blocks of the system are experimentally verified. The system has been designed with acoustic intercept and the resultant velocity curves are displayed on software oscilloscope on PC.