Increase in sustaining voltage of gate-turnoff thyristors by an innovative floating gate structure

The turnoff capability of a gate-turnoff thyristor is described by a sustaining voltage Vs which is the maximum reapplied voltage during current interruption. An innovative floating gate structure in which one of the two gate electrodes formed on both sides of the cathode emitter is connected to the external gate terminal provides a significant increase in Vs of more than 800 V from the 600 V of a conventional gate structure. This is attributed to the series gate conductance which is more than three times larger than that of the conventional gate structure during the tail period.