Development and verification of a theroretical framework for the evaluation of the residual ripple amplitude in DC/DC converters with spread-spectrum clocking

DC/DC converters are nowadays indispensable in the modern electronic world, starting from the realm of the power electronics and arriving to the most common uses like automotive, industrial equipment and also our smartphones. The first prototypes of DC/DC converters started to be projected in the early 20th century, but only after the 1960’s their use started to be massive due to the development of both transistors and, especially, semiconductor diodes. Technically speaking, DC/DC converters are used as intermediary among different energy levels for ensuring to each part of a device their required voltage level. In this way you can save space and store energy (differently from AC converters) maintaining at the same time a decent efficiency for their focused application, with peaks of 95% if used peculiar technologies (e.g. SiC used as semiconductor). There are two different types of converters: linear and switching. The linear converters exploit an internal linear element (e.g. a load resistor) to regulate the wanted output signal, while the switching ones convert a voltage level into another one. However, even if on the one hand the linear architecture results to be simpler, on the other hand the switching one keeps higher efficiency and lower heat generation. Furthermore, the switching converter allows to regulate the wanted output voltage level to a higher level with respect to the initial one using peculiar architectures (e.g. Boost). One of the main downsides of the DC/DC switching converters is the possible presence of high energy peaks in specific frequencies, especially in the lower ones. This phenomenon could result in the emission of radiations which can interfere in the well function of other electronic devices around, causing the so called EMI (ElectroMagnetic Interference). One way to reduce the EMI effect is modulating the clock edge, spreading the energy of the carrier in a larger bandwidth close to it, in order not to accumulate in a single frequency the total energy of the carrier. This modulation, called Spread Spectrum Clocking (SSC), however, reduces the EMI effect at the cost of lower performances, resulting in a reduction of working frequencies and higher ripple in the output signal. The work developed during this thesis concentrated into the application of the SSC on two different DC/DC switching converters based on a buck architecture. The first one was voltage controlled, while the second current-programmed and de- pending on the their working function, we concentrated on developing a theoretical framework of each circuit in order to be able to model and evaluate the residual ripple amplitude, given a specific input signal.