One of the main topics of nowadays research is the efficiency improvement of var- ious electronic systems, powered with a rechargeable battery or directly connected to the main power grid. This interest should be supported by the will to abandon energy generation methods typical of the past two centuries, like non-renewable sources, first among everything coal and liquid or gaseous fossil fuels. These sources have reached their life cycle end and damaged the environment. For these reasons the world is en- couraging the use of energy derived form renewable sources, moreover reducing losses is also a main concern. Following this trend, more stringent requirements have been developed like the U.S.