PI-EMI co-analysis of ground via effect

To get a good power integrity (PI) and low electromagnetic interference (EMI) in high-speed circuits, the ground via and/or decoupling capacitor is always applied by the engineers. An appropriate placement of the ground via can reduce the input impedance which is resulted from the resonance between two ground planes, and eliminate the noise source caused by the discontinuity of the signal via, where such noise can act as the feed of the patch-antenna-like ground plane pair. In this paper, we analyze the placement of the ground via when the noise source is located at different positions of the board, furthermore, we propose a PI-EMI co-analysis method based on equivalent source model to derive the relationship between the input impedance of the ground planes pair and its far field radiation.