This paper presents the study of a series-resonant inverter for the supply of a dielectric barrier discharge excimer lamp. Causal analysis, based on the fundamental properties of the load, is used to detail the reasoning which has led to this topology. In order to effectively control the lamp power, the operating mode of this converter combines discontinuous current mode and soft commutation (zero-current switching), obtaining low electromagnetic emissions and reduced switching losses as well. The model of the lamp is briefly presented, and it allows a simple state plane analysis to calculate all the electric variables involved in the converter and, consequently, to select the components of the supply. The mathematical relationships obtained from this process, for injected power control by means of the available degrees of freedom, are validated with simulations and experimental results.