The present invention concerns a device for generating a rectangular sustain voltage between the line scanning electrodes and the line common electrodes of luminous cells in a plasma panel. The device includes a first sustain amplifier connected to the line scanning electrode of the cells to produce the transitions of the first sustain voltage signal, and a second sustain amplifier connected to the line common electrode of the cells to produce the transitions of the second sustain voltage signal. It also includes an insulated voltage supply circuit which is connected directly to the line scanning electrodes and to the line common electrodes of the cells in order to hold the end-of-transition voltage on said line scanning electrodes and said line common electrodes.