Calculating electromagnetic coupling between isolated power islands by 2D-FDTD with equivalent circuits

Two-dimensional finite difference time domain (2D-FDTD) method is a very powerful electromagnetic numerical method for simulating electromagnetic(EM) problems of a complicated printed circuit board (PCB). However, due to the lack of transversal components of electric field intensities, it is hard to contain the coupling effect among isolated power/ground islands. In order to simulated the EM performance of the whole PCB, a set of equivalent circuits between adjacent two edges of isolated islands are used to calculate the coupling. First, the scattering parameters (S-parameters) of multiple ports are obtained from measurement by network analyzer or simulation by full wave EM solver. Then, a mode extraction approach is applied to those S-parameters to obtain the coupling modes. Finally, a set of equivalent circuits can be obtained. Those circuits can be combined with 2D-FDTD method to calculate signal integrity (SI), and power integrity (PI) including coupling between isolated islands.