Patent ID: 7786504

Claim:
A bidirectional PNPN silicon-controlled rectifier comprising: a P-type substrate; a N-type epitaxial layer formed on said substrate; a P-type middle doped area and two N-type wells all formed inside said N-type epitaxial layer with said two N-type wells respectively arranged at two sides of said P-type middle doped area; a first semiconductor area, a second semiconductor area and a third semiconductor area all formed inside said P-type middle doped area and all coupled to an anode, wherein said first semiconductor area is arranged in between said second semiconductor area and said third semiconductor area, and wherein a conduction type of said first semiconductor area is opposite to that of said second and third semiconductor area; and two P-type doped areas respectively formed inside said N-type wells and arranged at two sides of said P-type middle doped area, wherein each said P-type doped area has a fourth semiconductor area neighboring said P-type middle doped area and a fifth semiconductor area, and wherein both said fourth semiconductor area and said fifth semiconductor area are coupled to a cathode, and wherein a conduction type of said fourth semiconductor area is opposite to that of said fifth semiconductor area.