Implementation of a digital signal synthesizer with high spurious free dynamic range

Kılıç, Argun
Today’s analog modulators and upconverters are inadequate to synthesize and modulate signals with high ‘Spurious Free Dynamic Range’ (SFDR). Thus, the main objective of this thesis is to design and implement a ‘Digital Signal Synthesizer’ (DSS) that is capable of synthesizing signals between 50-100 MHz with 60dB SFDR and to modulate them variable symbol rates and modulation techniques with very high phase/frequency resolution and switching speed while keeping the amplitude modulation occurring during a modulated symbol duration as small as possible. In this thesis, digital words of the desired signals are first synthesized in a ‘Field Programmable Gate Array’ (FPGA) using ‘Direct Digital Synthesizer’ (DDS) fundamentals and then converted to analog signals with a high speed ‘Digital to Analog Converter’ (DAC). In order to attain the analog requirements, the system variables such as DAC analog performance, nonlinearities, sample and hold affects, DDS parameters, system clock, bandwidth requirements of analog filters and how they effect the output performance are studied. FPGA blocks that are capable of modulating and synthesizing desired signals are designed and programmed on a FPGA. Finally, single tone and modulated signals are synthesized with this DSS implementation and measured in order to verify this system’s performance and capabilities.


Analysis of circular waveguides coupled by axially uniform slots
Öztürk, Mensur; Çağlayan, Fatih; Department of Electrical and Electronics Engineering (2006)
The characteristics of slotted circular waveguides with different dimensions, including cutoff frequencies of TE and TM modes, impedance and modal field distributions will be analyzed using the generalized spectral domain approach. The Method of Moment will be applied, basis functions that include the edge conditions will be used and a computer program will be developed. Obtained results will be presented for different number, depth and thickness of coupling slots, and compared with available data to demons...
Analysis of slot coupled microstrip patch antennas
Ballıkaya, Elif; Aydın Çivi, Hatice Özlem; Department of Electrical and Electronics Engineering (2007)
Method of Moments (MoM)/Green’s function formulation is developed for the analysis of electromagnetic radiation from planar rectangular microstrip antennas with different feeding techniques. Investigated structures are microstrip line fed patch antenna, proximity coupled patch antenna and slot coupled patch antenna. For all these structures equivalent problems are defined. Then, integral equations where currents are the unknowns are obtained from boundary conditions and by using spectral domain representati...
Comparison of the intercarrier interference cancellation methods in OFDM systems
Etiler, Burkay; Tuncer, Temel Engin; Department of Electrical and Electronics Engineering (2007)
In OFDM systems carrier frequency offset is observed due to Doppler shift and transmitter-receiver frequency mismatches. This offset induces ICI (Intercarrier Interference). In this thesis, repeated data methods and pilot-aided carrier frequency offset(CFO) estimation methods and windowing techniques are used to mitigate the frequency offset problem and a performance comparison is made between these ICI cancellation techniques. Repeated data methods use only half of the bandwidth for information transmissio...
Implementation of a DF algorithm on an FPGA platform
İpek, Abdullah Volkan; Severcan, Mete; Department of Electrical and Electronics Engineering (2006)
In this thesis work, the implementations of the monopulse amplitude comparison and phase comparison DF algorithms are performed on an FPGA platform. After the mathematical formulation of the algorithms using maximum-likelihood approach is done, software simulations are carried out to validate and find the DF accuracies of the algorithms under various conditions. Then the algorithms are implemented on an FPGA platform by utilizing platform specific software tools. Block diagrams of the hardware implementatio...
Frame synchronization in OFDM systems
Gürsan, Hakan Yesari; Tuncer, Temel Engin; Department of Electrical and Electronics Engineering (2005)
In this thesis, we considered the problem of frame synchronization and channel estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. Since framing error may cause severe ISI and may disturb the orthogonality of the subcarriers, frame synchronization must be accomplished at the OFDM receiver. Furthermore, the effects of channel must be compensated to obtain the symbols accurately. We investigated several frame synchronization algorithms including a maximum likelihood (ML) synchronizer whic...
Citation Formats
A. Kılıç, “Implementation of a digital signal synthesizer with high spurious free dynamic range,” M.S. - Master of Science, Middle East Technical University, 2006.