A consideration on turn-off failure of GTO with amplifying gate

In this paper, using the high power buried gate GTOs of various n-base carrier lifetimes, the turn-off failure phenomena peculiar to the AG-GTO are investigated, under the conditions of short on-duration (30–200µs) and lagging current operation. From the results of this investigation, it was found that there are three kinds of the AG failure modes; the off-bias voltage for the AG is insufficient to turn-off the AG current, the “miss-gate current” flows before the turn-off of the AG is completed and the “miss-gate current” exceeds the sensitivity of the AG. As a result, the factors causing the AG failure and the desirable driving method are clarified.