Patent ID: 8537512

Claim:
An electronic device having input/output (I/O) and common terminals, comprising: a circuit core coupled between the I/O terminal and the common terminal; at least one substantially asymmetric electro-static discharge (ESD) clamp having first and second terminals, wherein the first terminal is coupled to one of the I/O terminal or the common terminal; and two opposed floating diode strings formed in a polycrystalline semiconductor, each of the diode strings having therein multiple diodes coupled in series, wherein the diode strings are parallel coupled to third and fourth terminals, wherein the third terminal is coupled to the second terminal of the ESD clamp and the fourth terminal is coupled to the other of the I/O terminal or the common terminal, and wherein a first diode string of the two opposed floating diode strings comprises a first plurality of diodes coupled in series, wherein a first diode of the first plurality of diodes includes a first region of a first conductivity type and a first doping density, a second region of the first conductivity type directly adjacent the first region and having a second doping density that is less than the first doping density, and a third region of a second conductivity type directly adjacent the second region, and wherein a second diode of the first plurality of diodes includes a fourth region of the first conductivity type directly adjacent the third region and having the first doping density, a fifth region of the first conductivity type directly adjacent the fourth region and having the second doping density, and a sixth region of the second conductivity type directly adjacent the fifth region, and wherein the third region of the first diode is electrically coupled with the fourth region of the second diode.