Patent ID: 8853560

Claim:
A printed circuit board having an analog circuit and a digital circuit, the printed circuit board in which an electromagnetic bandgap structure is disposed between the analog circuit and the digital circuit, the electromagnetic bandgap structure comprising: a first metal layer; a first dielectric layer, stacked in the first metal layer; a second metal layer, stacked in the first dielectric layer, and having a hole formed at a predetermined position; a second dielectric layer, stacked in the second metal layer; a metal plate, stacked in the second dielectric layer; a first via, penetrating the hole formed in the second metal layer and connecting the first metal layer and the metal plate; a third dielectric layer, stacked in the metal plate and the second dielectric layer; a third metal layer, stacked in the third dielectric layer; and a second via, connecting the second metal layer to the third metal layer, wherein the second metal layer has a greater area than the metal plate, wherein a plurality of second vias are formed, wherein the plurality of second vias connect the second metal layer to the third metal layer through an area excluding the area in which the metal plate is stacked, wherein the first via is only extended from the first metal layer to the metal plate such that the metal plate and the first via form a mushroom type structure, wherein the second vias are only extended from the second metal layer to the third metal layer, wherein a plurality of metal plates are formed, and the plurality of metal plates are separated from one another, and wherein a plurality of mushroom type structures are placed between the first metal layer and the third metal layer.