An ESD clamping device comprises a plurality of fingers each comprising a source region of first conductivity type formed in a substrate of second conductivity type, a drain region of said first conductivity type formed in the substrate, and a gate formed over the substrate and between the source and drain regions. At least one of the fingers each has an ESD implantation region formed in the substrate and partially underlying the drain region of the finger, the ESD implantation region being a heavily doped region of said second conductivity type. Furthermore, at least one of the fingers has a gate extension portion projecting from the gate and demarcating an additional region in at least the drain region of the finger, the additional region of said second conductivity type being electrically connected to at least one of the gate and the substrate of each of the fingers.