Patent ID: 6791146
Filing Date: 2004-09-14
Classification: H01L

Abstract:
A silicon controlled rectifier with a controlled guard ring structure comprising:a first lightly doped well region of a second conductivity type and a second lightly doped well region of a first conductivity type in a substrate having said first conductivity, wherein said second lightly doped well region adjacent to said first lightly doped well region, and said second conductivity type opposites to said first conductivity type; a first node is electrically coupled to a first heavily doped region of said second conductivity type and to a second heavily doped region of said first conductivity type, wherein an impurity concentration of each said heavily doped region is higher than each said lightly doped well region; a second node is electrically coupled to a fourth heavily doped region having said first conductivity type and to a third heavily doped region having said second conductivity type, wherein the polarity type of said second node opposites to said first node; a switch having a first terminal and a second terminal, wherein said first terminal is electrically coupled to said first heavily doped region and said second terminal is electrically coupled to a fifth heavily doped region having said second conductivity type within said first lightly doped region; and a control circuit is electrically coupled to said switch.