Common-mode noise reduction using floating conductor in LSI package

The authors proposed a method to reduce the common-mode current flowing on a wire harness attached to a printed circuit board (PCB). In this method, SMD inductors are placed on a power supply line and/or a ground line on a PCB to control balance of impedance of the power distribution network, and the common-mode current can be reduced. In this paper, the authors apply this reduction method to an LSI package, and propose a new structure of the LSI package with floating conductor which is called cover metal. The common-mode voltage is reduced about 20 dB with the package proposed in this paper.