Electro-static discharge(ESD)is always a serious threat to integrated circuits.To achieve higher robustness and a smaller die area at the same time,a novel protection structure for the output pad is proposed.The complementary SCR devices in this structure can protect not only the output under positive or negative stresses versus VDD or VSS,respectively,but also the power rails at the cost of almost no extra area.The robustness of the proposed structure is about three times higher than the conventional four-finger GGNMOS/GDPMOS structure in the same area condition. Electro-static discharge (ESD) is always a serious threat to integrated circuits. To achieve higher robustness and a smaller die area at the same time, a novel protection structure for the output pad is proposed. The complementary SCR devices in this structure can protect not only the output under positive or second stresses to VDD or VSS, respectively, but also the power rails at the cost of almost no extra area. robustness of the proposed structure is about three times higher than the conventional four-finger GGNMOS / GDPMOS structure in the same area condition.