Image Number 5 for United States Patent #6671147.
A double-triggered electrostatic discharge (ESD) protection circuit for coupling with a first voltage source and a second voltage source. The circuit includes a diode series and a transistor. The diode series comprises a plurality of serially connected diodes with the cathode of one diode connected to the anode of a subsequent diode. The positive terminal of the first diode in the diode series connects with the first voltage source. The gate terminal of the transistor connects with the anode of the last diode in the diode series. The substrate of the transistor connects with the cathode of the last diode in the diode series. The source terminal and the drain terminal of the transistor connect with the first voltage source and the second voltage source, respectively. By using double-triggered design, the ESD clamp device can be quickly triggered on to bypass ESD current. Therefore, the ESD protection circuit has a better protection capability to protect the IC in deep-submicron CMOS technologies against ESD damage.