| 摘要 |
PURPOSE:To remove an exclusive use input electrostatic protecting circuit from the l/O cell of a CMOS gate array semiconductor integrated circuit by providing the input electrostatic protecting circuit composed of transistors used as output buffers. CONSTITUTION:An input electrostatic protecting circuit composed by using transistors used as output buffers is provided in a CMOS gate array semiconductor integrated circuit. For example, MOSFET Qp1 and Qn1 are used as input buffer MOSFETs, and MOSFET Qp2 and Qn2 are used as output buffer MOSFETs. When an I/O cell is used as an input buffer, the MOSFET Qp1, Qn1 form inverters, the source of the MOSFET Qp2 is connected to the gate of the MOSFET Qp1, Qn1, the gate and the drain are connected to a power source VDD, the drain of the MOSFET Qn2 is connected to the gates of the MOSFET Qp1, Qn1, and the gate and the source are connected to a ground. Thus, the I/O region is reduced to decrease the size of a chip. |
