| 摘要 |
PURPOSE:To protect a gate oxide film without using a current limiting resistor between an input terminal and an MOS transistor, by connecting diodes, which have reverse dielectric strength lower than the dielectric strength between the source and the drain of each MOS type field effect transistor in use, to bipolar transistors, whose base regions are fixed to the lowest potential or the highest potential of a circuit, in parallel. CONSTITUTION:A CMOS inverter circuit is composed of the following parts: a P-channel MOS transistor M1 constituting the inverter; an N-channel MOS transistor M2; diodes D1-D5, whose reverse dielectric strengths are lower than the dielectric strengths between the sources and the drains of the MOS transistors m1 and m2; and the like. For the case positive electrostatic stress with respect to VDD is present, a transistor T1 is connected to the diode D1 in this constitution. Therefore the time required to obtain the ON state is shortened, and a parasitic series resistance component can be decreased. For the case negative electrostatic stress with respect to VDD is applied, the dielectric strength of the diode D1 is designed so that it is especially low. Therefore protection becomes possible. |
