Patent ID: 7301741

Claim:
For use with a plurality of external terminals of an integrated circuit that may be exposed to an electrostatic discharge (ESD) event, a rail clamp circuit comprising: a first power supply voltage rail; a second power supply voltage rail; a multiple independent gate field effect transistor (MIGFET) having a source/drain path coupled between said first and second power supply voltage rails, a first gate and a second gate; and an ESD event detector circuit coupled between said first and second power supply voltage rails, and having first and second output terminals respectively coupled to said first and second gates of said MIGFET, wherein in response to an ESD event between said first and second power supply voltage rails, said ESD event detector circuit provides a voltage to said first gate to adjust a threshold voltage of said MIGFET while providing a voltage to said second gate to make said MIGFET conductive with relatively high conductivity.