This paper deals with cascade multilevel inverters. It focuses on asymmetrical topologies where the cell input voltages are of different values. These hybrid topologies might be interesting for several applications. One of the main benefit is the high resolution that can be obtained with a small number of cells. Another benefit is the higher energetic efficiency of the inverter alone. Nevertheless, the need of DC-DC converters to supply the cells of reversible multilevel converters increases the cost and losses of such inverters. It limits their application field. This paper gives an overview of the design rules of these inverters. It highlights some of their limitation and the way to get round these obstacles.