| 摘要 |
PURPOSE: An electrostatic discharge(ESD) protection circuit is provided to reduce an area occupied by the ESD protection circuit, by forming a well guard ring having a high density n-type active region and a high density p-type active region and by forming a transistor for protecting ESD. CONSTITUTION: A resistor unit is connected between a pad and a main chip. A field bipolar transistor(43) for protecting the ESD includes the well guard ring having a plurality of high density impurity regions. The collector of the field bipolar transistor is connected to the output terminal of the pad, and the emitter and the base of the field bipolar transistor are grounded and connected between the pad and the resistor unit. An n-channel metal-oxide-semiconductor(NMOS) transistor of a diode type is connected between the resistor unit and the main chip while directly connected to a power source.
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