A double-interdigitated GTO switch

Abstract

This work presents the basic structure and operation principles of a novel power switch: the electrothermally failure-safe double-interdigitated GTO thyristor. The 4 × 4 mm area test devices packed into TO-220 cases, fabricated according to the design guidelines outlined in this work, exhibited the following many-fold advantages over their conventionally interdigitated counterparts of the same class (identical device area and case): an 80-percent boost in the value of I ATO , an enhanced value of the turn-off gain K off ; fast turn-off and high reverse-blocking capability; higher gains K off at reduced turn-off × a reasonable forward voltage drop; and an enhanced electrothermal reliability, translated into failure-safe operation at high commutation frequencies. These unique features are accompanied by high turn-on sensitivity and immunity to noise (high dV/dt capability). These unique features that the developed GTO switch is endowed with are inherent to a new gate-cathode concept with two interdigitation levels (TIL). The foremost merit of the TIL pattern consists in the novel way in which wide interdigitated fingers produce effects typical of narrow-finger design. It is noteworthy that the technology for fabrication of the low-cost and unsophisticated double-interdigitated pattern is self-aligned.