ESD protection circuit with low parasitic capacitance

摘要

An ESD protection circuit includes a silicon controlled rectifier coupled between a circuit pad and ground for bypassing an ESD current from the circuit pad during an ESD event. An MOS transistor, having a source shared with the silicon controlled rectifier, is coupled between the pad and ground for reducing a trigger voltage of the silicon controlled rectifier during the ESD event. The silicon controlled rectifier has a first diode serially connected to a second diode in an opposite direction, between the pad and the shared source of the MOS transistor, for functioning as a bipolar transistor. In a layout view, a first area for placement of the first and second diodes is interposed between at least two separate sets of second areas for placement of the MOS transistor.