Image Number 5 for United States Patent #5838549.
In semiconductor modules having a plurality of semiconductor devices mounted on a multilayer printed circuit boards as the processing speed increases, a short circuit current flowing through CMOS devices in the semiconductor devices during operation can cause noise because of ground inductance or power supply inductance. This noise can result in erroneous operations. To solve this problem, the power supply layer or grand layer that is connected to either the power supply terminal Vcc or the ground terminal Gnd of each semiconductor memory, which is located farther from the connection terminals, is arranged closer to the semiconductor memories with this arrangement, the short circuit current flowing through the semiconductor memories is more strongly magnetically coupled with the power supply layer or ground layer arranged close to them. Thus, it is possible to reduce the effective inductance. This, in turn, reduces noise, making it possible to provide a semiconductor module with an increased processing speed.