ELECTROSTATIC DISCHARGE CIRCUIT

摘要

PURPOSE: To protect a semiconductor integrated circuit against electrostatic discharge. CONSTITUTION: To shunt a surge voltage generated owing to electrostatic discharge a bipolar transistor(TR) 35 and a bipolar diode 36 are connected to an input pad 21 of the integrated circuit. They shunts an excessive current from an area which is easily damaged with a uniform current distribution that minimizes the damage. A diode clamp and a bipolar circuit 25 which has an optimum reverse bias yield voltage from a collector to a base are used. To improve immunity to the electrostatic discharge which is applied as a positive voltage to a source voltage VSS, reverse bias yield voltages of a diode and a transistor operating as a collector/base diode are reduced in areas 38 and 39 respectively. This circuit provides easy low-cost technology which achieves protection against electrostatic discharge in the most standard CMOS manufacture process without adding any other process.