A Consideration on Turn-Off Failure of GTO with Amplifying Gate

Using the high-power buried-gate GTO´s of various n-base carrier lifetimes, the turn-off failure phenomena peculiar to the amplifying gate (AG) GTO are investigated, under the conditions of short on-duration (30-200 ¿s) and lagging current operation. From the results of this investigation, it was found that there are three kinds of AG failure mode: 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.