This invention discloses an electrostatic discharge (ESD) protection circuit that comprises a substrate of a predetermined type, at least one MOS transistor being coupled to a pad of an integrated circuit for dissipating an ESD current from the pad during an ESD event, a substrate contact region, and at least one floating diffusion region formed in a substrate area between the MOS transistor and the substrate contact region for reducing a trigger-on voltage of the MOS transistor during the ESD event.