The aim of this thesis is to design an amplifier for electrostatic and dynamic headphones with D/A converter integrated into one device. This device is controlled by a microcontroller The thesis deals mainly with the design, realisation and testing of all functional blocks of the device.

This diploma thesis deals with the design of a laboratory measurement tool with ADC converter for audio and low frequency signals. In the introduction part a theoretical background of the ADC and DAC conversions are outlined. In the next chapters the technical solution of the laboratory converter is presented, including DAC with integrated circuit AD1852 and completed with digital audio receiver CS8416. This circuit secures compatibility with external audio devices with digital interfaces, like SPDIF or AES3. The digital receiver and audio DAC are added with serial communication interface for setup of the most audio and input parameters. This setup is operated by external microcontroller ATmega32 and original firmware. The thesis contains block diagram and schematic layout of the laboratory converter, including complete technical documentation for the construction and design.

This master’s thesis is about design and realization of a digital controlled power supply. In the introduction there is defined a basic princip and division of the power supplies. Furthermore, there are considered two design realisations of digital controlled power supllies. The first one will be controlled by D/A converter and the second one will be controlled by digital potentiometers. Consequently, there is in the master’s thesis designed controlled part which controls output parameters of supply. The core of the controlled part is microcontroller ATmega16. Output parameters are displayed on LCD display and are set by 4x4 matrix keypad. In the last part there is designed connection between PC and microcontroller by the help of converter FT232BM. Subsequently, there is designed the rectifier with a filter and electronic switching of the fan. At the end of the thesis is resolved the placement of the various component parts to the component box.

<p>Master thesis work at ITN (Department of Science and Technology) in the areas of A/D-construction and RF-circuit design. Major goal of project were to research suitable possibilities for implementations of direct conversion in transceivers operating in the 160MHz band, theoretic study followed by development of components in the construction environment Cadence. Suitable A/D- converter and other important parts were selected at the end of the theoretic study. Subsampling technique was applied to make A/D sample requirements more realistic to achieve. Besides lowering requirements on A/D-converter it allows a more simple construction, which saves more components than subsampling adds. Subsampling add extra noise, because of that an A/D-converter based on the RSD algorithm was chosen to improve error rate. To achieve high bit-processing rate compared to the used number of transistors, pipeline structure were selected as conversion method. The receiver was that part which gained largest attention because it’s the part which is most interesting to optimise. A/D-conversion is more difficult to construct than D/A conversion, besides there’s more to gain from eliminating mixers in the receiver than in the transmitter.</p>

Master thesis work at ITN (Department of Science and Technology) in the areas of A/D-construction and RF-circuit design. Major goal of project were to research suitable possibilities for implementations of direct conversion in transceivers operating in the 160MHz band, theoretic study followed by development of components in the construction environment Cadence. Suitable A/D- converter and other important parts were selected at the end of the theoretic study. Subsampling technique was applied to make A/D sample requirements more realistic to achieve. Besides lowering requirements on A/D-converter it allows a more simple construction, which saves more components than subsampling adds. Subsampling add extra noise, because of that an A/D-converter based on the RSD algorithm was chosen to improve error rate. To achieve high bit-processing rate compared to the used number of transistors, pipeline structure were selected as conversion method. The receiver was that part which gained largest attention because it’s the part which is most interesting to optimise. A/D-conversion is more difficult to construct than D/A conversion, besides there’s more to gain from eliminating mixers in the receiver than in the transmitter.

High-speed and high-resolution digital-to-analog converters (DACs) are vital components in all telecommunication systems. Radio-frequency digital-to-analog converter (RFDAC) provides high-speed and high-resolution conversion from digital domain to an analog signal. RFDACs can be employed in direct-conversion radio transmitter architectures. The idea of RFDAC is to utilize an oscillatory pulse-amplitude modulation instead of the conventional zero-order hold pulse amplitude modulation, which results in DAC output spectrum to have high energy high-frequency lobe, other than the Nyquist main lobe. The frequency of the oscillatory pulse can be chosen, with respect to the sample frequency, such that the aliasing images of the signal at integer multiples of the sample frequency are landed in the high-energy high-frequency lobes of the DAC frequency response. Therefore the high-frequency images of the signal can be used as the output of the DAC, i.e., no need to the mixing stage for frequency up-conversion after the DAC in the radio transmitter. The mixing stage however is not eliminated but it is rather moved into the DAC elements and therefore the local oscillator (LO) signal with high frequency should be delivered to each individual DAC element. In direct-conversion architecture of IQ modulators which utilize the RFDAC technique, however, there is a problem of finite image rejection. The origin of this problem is the different polarity of the spectral response of the oscillatory pulse-amplitude modulation in I and Q branches. The conditions where this problem can be alleviated in IQ modulator employing RFDACs is also discussed in this work. ΣΔ modulators are used preceding the DAC in the transmitter chain to reduce the digital signal’s number of bits, still maintain the same resolution. By utilizing the ΣΔ modulator now the total number of DAC elements has decreased and therefore the delivery of the high-frequency LO signal to each DAC element is practical. One of the costs of employing ΣΔ modulator, however, is a higher quantization noise power at the output of the DAC. The quantization noise is ideally spectrally shaped to out-of-band frequencies by the ΣΔ modulator. The shaped noise which usually has comparatively high power must be filtered out to fulfill the radio transmission spectral mask requirement. Semi-digital FIR filter can be used in the context of digital-to-analog conversion, cascaded with ΣΔ modulator to filter the out-of-band noise by the modulator. In the same time it converts the signal from digital domain to an analog quantity. In general case, we can have a multi-bit, semi-digital FIR filter where each tap of the filter is realized with a sub-DAC of M bits. The delay elements are also realized with M-bit shift registers. If the output of the modulator is given by a single bit, the semi-digital FIR filter taps are simply controlled by a single switch assuming a current-steering architecture DAC. One of the major advantages is that the static linearity of the DAC is optimum. Since there are only two output levels available in the DAC, the static transfer function, regardless of the mismatch errors, is always given by a straight line. In this work, the design of SDFIR filter is done through an optimization procedure where the ΣΔ noise transfer function is also taken into account. Different constraints are defined for different applications in formulation of the SDFIR optimization problem. For a given radio transmitter application the objective function can be defined as, e.g., the hardware cost for SDFIR implementation while the constraint can be set to fulfill the radio transmitter spectral emission mask.

This master’s thesis deals with design of two channel digital to analog converter for automotive applications. In first part, different topologies of D/A converters and their properties are discussed, with focus on current steering topology. Second part deals with design of convertor topology and current steering application. In third part, all parts of designed convertor are described and simulations results are presented. The designed two channel D/A converter has differential current output with 11b resolution per channel.

This work deals with the design of a galvanically isolated converter of continuous analog signals and the design of a galvanically separated converter of digital TTL signals to HTL signals. The device is complemented by a STM32 microprocessor, which ensures the connection of analog input and output. The result of the work is the circuit structure of individual units, the results of simulations of important units, complete data for the production of device and measured values of individual units.

The objective of this thesis is a design of a development kit, which is used in laboratories during the lessons of Theory of analog to digital conversion subject. This device is adapted for basic measuring and understanding of digital to analog (D/A) and analog to digital (A/D) converters and contains sigma-delta A/D converter made of basic elements, D/A converter with R-2R resistor net, active low pass frequency filter (Sallen-Key), PWM generator, SAR A/D converter with 16 b resolution, reference voltage source and module for measuring integral and differential nonlinearity of A/D converters. The modules are available connect to each other via jumpers and they are driven by microcontroller. This solution gives various modes of operation, which can be selected by user via buttons. Development kit has five BNC connectors for securing connectivity to an oscilloscope or a signal generator. The device also contains universal serial bus connectivity for use with personal computer or laptop, which is really useful with Matlab software for automation processing of measuring.

Master's Thesis deals with the complete proposal of light adaptability A/D converter. In the second chapter there are describes types of sensors. Third one describes the most used methods of light adaptability. In the fourth chapter there is describe the adaptability A/D conversion. Chapter 5 describes the block diagram. In the sixth chapter there is the design of all blocks of A/D converter. Finally in the chapter 7 there are construction documents for realization.