[1] GTOs, as opposed to normal thyristors, are fully controllable switches which can be turned on and off by their gate lead.

Thyristors are switched on by a gate signal, but even after the gate signal is de-asserted (removed, reverse biased), the thyristor remains in the on state until a turn-off condition occurs (which can be the application of a reverse voltage to the terminals or a decrease of the forward current below a certain threshold value known as the holding current).

GTO thyristors suffer from long switch-off times, whereby after the forward current falls, there is a long tail time where residual current continues to flow until all remaining charge from the device is taken away.

Reverse blocking capability adds to the forward voltage drop because of the need to have a long, low-doped P1 region.

Unlike the insulated gate bipolar transistor (IGBT), the GTO thyristor requires external devices (snubber circuits) to shape the turn-on and turn-off currents to prevent device destruction.

If this rating is exceeded, the area of the device nearest the gate contacts will overheat and melt from overcurrent.

Reset of the saturable reactor usually places a minimum off-time requirement on GTO-based circuits.

Substantial snubber circuits are added around the device to limit the rise of voltage at turn off.

The minimum on- and off-time is handled in DC motor chopper circuits by using a variable switching frequency at the lowest and highest duty cycle.