Contribuții privind compatibilitatea electromagnetică a circuitelor și sistemelor digitale / Contributions regarding electromagnetic compatibility of digital circuits and systems

Increasing the operating frequency, miniaturization of the integrated circuits, parallel processing and reduction of supply voltage affect the ability of electronic circuits and systems to function properly in a complex electromagnetic environment with a high degree of occupation of the radio spectrum. The doctoral thesis studies different aspects regarding the electromagnetic compatibility of digital circuits and systems starting from the band of trapezoidal impulses that are transmitted through such systems. Single microstrip lines made on a Rogers 4003 C low-loss substrate in the 0.5 GHz, 50 GHz frequency band are studied. The reflection, transmission and coupling parameters as a function of the trace separation are determined by simulations and measurements. Also, the differential lines made on a Rogers 4003 C low-loss substrate are analyzed in the time and frequency domains. The calculated electromagnetic parameters in the frequency domain, up to 50 GHz, are used to create an equivalent scheme in the time domain that is used to study the effect of the differential line on the front times and amplitude of the digital signals. A phenomenon that affects the quality of the signal transmitted through digital connections is the radiation that occurs during transient regimes. The levels of the interference signals generated by different configurations (vias, vias connected to matched and opened microstrip lines, in the 1-40 GHz range, are analyzed by finite element simulations and by measurements. Another aspect studied in the PhD thesis refers to the radiations produced inside a desktop-type enclosure that are transmitted to the outside through the slots made for the input-output devices. The dependence of the radiated electromagnetic field is analyzed as a function of the angular coordinates and the maximum amplitude of the interferences produced is determined in the frequency band 1- 40 GHz.