Exemplary embodiments provide structures and methods for power devices with integrated clamp structures. The integration of clamp structures can protect the power device, e.g., from electrical overstress (EOS). In one embodiment, active devices can be formed over a substrate, while a clamp structure can be integrated outside the active regions of the power device, for example, under the active regions and/or inside the substrate. Integrating clamp structure outside active regions of power devices can maximize the active area for a given die size and improve robustness of the clamped device since the current will spread in the substrate by this integration.