| 摘要 |
PURPOSE:To prevent the electrostatic breakdown of an MOS.IC by simple constitution by connecting a diffusion resistor and an MOSFET for clamping voltage between an external terminal and an input MOSFET and previously connecting a depletion type MOSFET for applying back bias voltage at a node between the external terminal and the diffusion resistor. CONSTITUTION:A diffusion resistor R1 and an MOSFET element Q1 for clamping in which a gate and a source are connected in common are connected in series between an external terminal P1 and an input MOSFET element Q2 to constitute an input protective circuit, and a many pair of the circuits are connected in parallel, thus manufacturing an MOS.IC. In the constitution, a depletion type MOSFET element Q3 supplying back bias voltage Vbb is mounted at a node between the terminal P1 and the diffusion resistor R1, and a base in the element Q3 is connected at the node. Accordingly, the element Q3 is turned ON when static electricity is generated in the external terminal by charging, and the input protective circuits are operated. |
