The system has: a set of at least two electric current generators, at least one capacitor and activation/deactivation devices for the electric current generators; the electric current generator being connected in parallel with one another and the capacitor being connected in series with the electric current generators, the activation/deactivation devices controlling the generators by a digital stream allowing control of the intensity of the electric current entering the capacitor and generating a trapezoidal voltage signal at the terminals of the capacitor, the analog signal being reconstructed through interpolation of the trapezoidal signal.