Patent ID: 6034552
Filing Date: 2000-03-07
Classification: H01L

Abstract:
An apparatus for improving the ESD robustness of driving-current-programmable CMOS output buffers in cell libraries, comprising:a connection to an output pad;a connection to a pre-buffer circuit;a finger-type output CMOS having a plurality of poly-gate fingers connected to said output pad connection and with at least one CMOS output buffer finger connected to said pre-buffer circuit connection and the remaining unused CMOS output buffer fingers connected to one of two voltage sources; andmeans for dynamically floating the gate of the unused CMOS output buffer during ESD stress from an ESD voltage on said output pad connection, so that the unused CMOS output buffer can be turned ON to bypass the ESD current, said means comprising:a resistance connected between said two voltage sources;a capacitance connected between said resistance and said one of said two voltage sources; anda small-dimension CMOS device having its drain connected to the gate of said unused CMOS buffer, its source connected to said one of said two voltage sources, and its gate connected between said resistance and said capacitance.