Patent ID: 8680620

Claim:
An apparatus for providing protection from transient electrical events, the apparatus comprising: a substrate; a first pad and a second pad disposed over the substrate; wherein the substrate comprises a first well, a second well, and a third well, wherein the first well has a doping of a first type, wherein the second and third wells have a doping of a second type opposite to the first type, wherein the second well is disposed on a first side of the first well, wherein the third well is disposed on a second side of the first well opposite the first side; wherein the substrate further comprises a fourth well and a fifth well, wherein the fourth well has a doping of the first type and is disposed on a side of the second well opposite the first well, and wherein the fifth well has a doping of the first type and is disposed on a side of the third well opposite the first well; wherein the substrate further comprises a first active region, a second active region, a third active region, a fourth active region, a fifth active region, and a sixth active region, wherein the first and second active regions have a doping of the second type, wherein the fifth and sixth active regions have a doping of the first type, wherein the first and fifth active regions are disposed in the second well and are electrically coupled to the first pad, wherein the second and sixth active regions are disposed in the third well and are electrically coupled to the second pad, wherein the third active region is disposed along a boundary of the first and second wells and the fourth active region is disposed along a boundary of the first and third wells; and a first implant blocking structure and a second implant blocking structure, the first implant blocking structure disposed between the third and fifth active regions and the second implant blocking structure disposed between the fourth and sixth active regions; wherein the first pad is disposed over the fourth well, and wherein the second well, the first well, the third well, and the fifth well each comprise annular rings surrounding the fourth well, wherein the second well is disposed between the fourth and first wells, and wherein the third well is disposed between the fifth and first wells; and wherein the second well, the first well, and the third well are configured to operate as an emitter/collector, a base, and a collector/emitter of a bi directional bipolar transistor, respectively, such that the apparatus is configured to provide bi directional blocking protection from a transient electrical event received between the first and second pads.