Input circuit

Abstract

Abstract PURPOSE:To obtain an input circuit which is strong against a surge by connecting a gate of a load MOS transistor connected with a drain in the midway of wirings for transmitting a signal to the gate of an input stage transistor with a portion separated through a resistor at the input stage transistor side from the position connected with the drain. CONSTITUTION:When a surge of high voltage is applied to an input pad 11, the surge voltage is lowered to the prescribed degree by a protecting circuit 16. This voltage is further decreased by a resistor 19 and applied to one position 18 of wirings 12, i.e., the drain of an MOS transistor 17. The voltage applied to the first position 18 is further reduced by a resistor 22, and applied to the third position 23 of the wirings 12, i.e., the gate of the transistor 17. Thus, the voltage applied to the gate of the transistor 17 is lowered by the voltage drop by the resistor 22 as compared with the conventional one. Thus, the gate insulating film damage of the transistor 17 hardly occurs, thereby enhancing the surge withstand voltage.

Inventors

• 👤 Kiyoharu Oikawa
• 👤 清春 笈川

Bibliographic Details