Experimental Evaluation of Isolation Effect on Printed Circuit Board with Gapped Power Plane

When the digital and the analog circuits are mounted on a printed circuit board (PCB), the gapped digital and analog power planes are often used as the isolation method. In this case, three layers (digital power plane, ground plane, analog power plane) are needed for a perfect isolation between a digital power plane and an analog power plane. However, if it is possible to allocate only two layers for these three planes, the gapped planes in the same layer are used as the power planes. The gapped planes cause an increase of a radiation because the electromagnetic noise on one power plane couples to another power plane. In order to suppress a radiation, it is necessary to isolate both power planes. For this reason, the isolation method was estimated experimentally. And we estimated radiation from PCB with various gapped planes.