Gate turn-off thyristors (GTOs) are four-layer PNPN devices that act as switches, rectifiers, and voltage regulators. Like other thyristors, GTOs can be turned on by the application of a positive gate signal (g > 0); however, unlike other more conventional devices that can be turned off only at a zero crossing of current, GTOs can be turned off at any time by the application of a gate signal equal to zero.
