Patent ID: 9536869
Date: 2017-01-03
CPC Classifications: H01L

Claim:
1. An electrostatic discharge protection apparatus, comprising: a stack arrangement having: a first electrostatic discharge protection element comprising a first terminal, and a second terminal; and a second electrostatic discharge element comprising a first terminal, and a second terminal, the first electrostatic discharge protection element serially coupled to the second electrostatic discharge protection element, wherein the first electrostatic discharge protection element includes a transistor having a collector terminal, an emitter terminal, and a base terminal connected to the emitter terminal; the stack arrangement to provide a bias potential between the first and second electrostatic discharge protection elements based on a breakdown voltage of the first and second electrostatic discharge protection elements; the stack arrangement further comprises a clamp arrangement including a first voltage clamp serially coupled to a second voltage clamp, the clamp arrangement to provide a further bias potential across the first and second electrostatic discharge protection elements responsive to a breakdown voltage of each of the first and second voltage clamps, wherein a potential at the node between the first and second electrostatic discharge protection elements is substantially equal to a potential at a node between the first and second voltage clamps; and the second electrostatic discharge protection element is further inhibited from responding to a parasitic event at potentials below the further bias potential in response to the breakdown voltage of the first and second electrostatic discharge protection elements being higher than the breakdown voltage of the first and second voltage clamps.