Power and ground phase relation in LSI power distribution network at common-mode noise reduction

We derived expressions of power and ground voltage noises for reducing common-mode voltage in a power distribution network of an LSI and found that they have the same amplitude and a phase difference approaching 180°. To confirm this, we performed an experiment using a test board with a cover-metal structure-essentially, a floating conductor in an LSI package to reduce common-mode voltage. The evaluation was performed using an instrument that can measure the amplitude and phase difference of two channels in synchronization and calculate common-mode and differential-mode voltages. Results demonstrated phenomena similar to the expressions we derived.