Spur Level Reduction in Direct Digital Synthesizer

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Sabouri, Behnam | 2018

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 50999 (05)
University: Sharif University of Technology
Department: Electrical Engineering
Advisor(s): Akbari, Mahmoud; Banai, Ali
Abstract:
Direct digital synthesizers (DDS) are one type of frequency synthesizer that are used for creating arbitrary waveforms from a reference clock with fixed-frequency and have various applications in signal generators, local oscillators in telecommunication systems, mixers, modulators and part of phase-locked loop.Despite of numerous advantages of direct digital synthesizers like high accuracy, fast switching ability, low power consumption and etc, beacuse of some available alternative errors in its structure like phase truncation, Inside band of desired output signal, independent unwanted signals namely spur were created. Spurs creat trouble in the use of sensor or radar systems and limit the performance and efficiency of radar or sensor. This project's goal is spurs level reduction in direct digital synthesizer's output by one technique namely dithering and implementation of it by a system based FPGA. For this purpose, a minimum noise is created by linear feedback shift register as pseudo random number generator and this random numbers are added to direct digital synthesizer's phase or amplitude for destroying the periodicity of errors and reducing the level of spurs’s power
Keywords:
Dithering ; Spurious ; Direct Digital Synthesizer (DDS) ; Frequency Synthesizer ; Spur Level Reduction

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