US Patent 7087968 Electrostatic discharge protection circuit and semiconductor circuit therewith

An ESD protection circuit is adapted for an integrated circuit with a first power source and a second power source. The ESD protection circuit comprises a first silicon controlled rectifier (SCR), a second silicon controlled rectifier, and a parasitic diode. The gate of the first silicon controlled rectifier is coupled to a first power source, and the gate of the second silicon controlled rectifier is also coupled to the first power source line.