High voltage transistor protection technique and switching circuit for integrated circuit devices utilizing multiple power supply voltages

摘要

A high voltage transistor protection technique and switching circuit of especial applicability to integrated circuit devices utilizing multiple power supply voltages. In accordance with the technique of the present intention, the problems inherent in the amount of on-chip die area consumed and speed degradation of prior art circuit implementations are overcome by furnishing a substantially direct current voltage VHVP to the gate of a first transistor of a series connected thin gate oxide pair wherein VHVP<=VDSMAX (the maximum gate-to-source voltage of the first transistor) and VHVP<=VDSMAX+Vt (the maximum drain-to-source voltage of the second transistor plus the threshold voltage of the first transistor).