Patent ID: 8675322

Claim:
An electrostatic discharge (ESD) protection device, electrically connected to a pad, the ESD protection device comprising: K PNP transistors, wherein an emitter of the 1 st PNP transistor is electrically connected to the pad, a base of the i th PNP transistor is electrically connected to an emitter of the (i+1) th PNP transistor, and collectors of the PNP transistors are electrically connected to a ground, wherein K is a positive integer, i is an integer, and 1≦i≦(K−1); and a protection circuit, for providing a discharge path, wherein an electrostatic signal from the pad is conducted to the ground through the discharge path and the PNP transistors, and the protection circuit comprises two MOS transistors having the same channel, wherein when the protection circuit comprises the two MOS transistors, the two MOS transistors are electrically connected in series between a base of the K th PNP transistor and the ground.