Patent ID: 8106460

Claim:
An insulated gate semiconductor device comprising: a semiconductor substrate; a plurality of transistor cells of an insulated gate semiconductor element formed in the semiconductor substrate so as to define an operating region in the semiconductor substrate; a gate pad electrode disposed on the semiconductor substrate and connected to gate electrodes of the transistor cells; and a group of protection diodes disposed on the semiconductor substrate outside the operating region, wherein the group of protection diodes comprises a first protection diode and a second protection diode that are connected to each other in parallel, the first protection diode has a plurality of pn junctions that are formed between a p type semiconductor region and an n type semiconductor region and are concentric closed-loops having a first center, and the second protection diode has a plurality of pn junctions that are formed between a p type semiconductor region and an n type semiconductor region and are concentric closed-loops having a second center different from the first center.