Abstract: A first clamp circuit and a second clamp circuit stacked thereon in vertical respectively for clamping unwanted level voltages are provided between the high potential side power source and low potential side power source and an intermediate node formed by vertical stacking of the first clamp circuit and second clamp circuit is coupled with the power source for internal circuit. Since a capacitor originally provided in the internal circuit is allocated in parallel to the first clamp circuit, impedance is reduced due to existence of the capacitor and potential difference due to over-current flowing in the chip is reduced. Accordingly, potential difference due to over-current flowing into the chip may be reduced and static electricity dielectric strength can be improved by allowing higher over-current. Thereby, impedance when the clamp circuits are stacked in two stages.

Abstract: A first clamp circuit and a second clamp circuit stacked thereon in vertical respectively for clamping unwanted level voltages are provided between the high potential side power source and low potential side power source and an intermediate node formed by vertical stacking of the first clamp circuit and second clamp circuit is coupled with the power source for internal circuit. Since a capacitor originally provided in the internal circuit is allocated in parallel to the first clamp circuit, impedance is reduced due to existence of the capacitor and potential difference due to over-current flowing in the chip is reduced. Accordingly, potential difference due to over-current flowing into the chip may be reduced and static electricity dielectric strength can be improved by allowing higher over-current. Thereby, impedance when the clamp circuits are stacked in two stages.