US Patent 7566595 Method of making and using guardringed SCR ESD protection cell

Methods and circuits are disclosed for protecting an electronic circuit from ESD damage using an SCR ESD cell. An SCR circuit is coupled to a terminal of an associated microelectronic circuit for which ESD protection is desired. The SCR used in the ESD cell of the invention is provided with a full guardring for shielding the SCR from triggering by fast transients. A resistor is provided at the guardring for use in triggering the SCR at the onset of an ESD event. Exemplary preferred embodiments of the invention are disclosed with silicide-block resistors within the range of about 2-1000 Ohms or less.