Diode-triggered bidirectional silicon controlled rectifier and circuit

A diode-triggered bidirectional silicon controlled rectifier, comprising a silicon controlled rectifier (SCR) and a diode string, the silicon controlled rectifier having an anode and a cathode and comprising:

• a P-type substrate;
• a first P well formed in the P-type substrate, a first P-type doped region and a first N-type doped region being formed in the first P well;
• a second P well formed in the P-type substrate, a third N-type doped region and a fourth P-type doped region being formed in the second P well;
• and
• an N well formed in the P-type substrate, a second P-type doped region, a second N-type doped region and a third P-type doped region being formed in the N well;
• wherein the first N-type doped region and the third P-type doped region are electrically connected with the anode;
• the third N-type doped region and the second P-type doped region are electrically connected with the cathode;
• the second N-type doped region is electrically connected with a positive electrode of the diode string, and the first P-type doped region and the fourth P-type doped region are electrically connected with a negative electrode of the diode string.