In one embodiment, a filter structure that integrates one plate of a capacitor with an electrode of a transient voltage device. The filter structure includes a well region of one conductivity type formed in semiconductor substrate of an opposite conductivity type. The well region forms one plate of the capacitor and an electrode of the transient voltage suppression device. A dielectric layer is formed over a portion of the well region and a conductive layer is formed overlying the dielectric layer to provide a second plate of the capacitor. The dopant concentration of the well region provides a constant capacitance/voltage characteristic for the filter structure when a selected voltage range is applied to plates of the capacitor.