A shielded circuit board includes a first metal layer with a first surface area, and first and second portions. A second metal layer includes first and second surface areas. At least one signal transmission line is arranged in a first dielectric material, the first dielectric material separating the first portion of the first metal layer and a first portion of the second metal layer. The first surface area of the first metal layer is arranged on the first portion facing the first surface area of the second metal layer and is arranged on the second portion facing the second surface area of the second metal layer. A method relates to shielding a circuit board.