Hybridized 3D-FDTD and circuit simulator for analysis of PCB via´s signal integrity

In this paper, the equivalent circuit model containing two pairs of vias is established, and a hybrid method is applied, which combines the full-wave finite difference time domain (FDTD) with an S-parameter based macromodel by using the rational function approximation and circuit simulation. The electromagnetic feature of the model is described by S-parameters, result of the simulation of FDTD. The vector fitting method is adopted to perform the rational function approximation of complex pole pairs. This method is robust and can supply results precise enough for the procedure of macromodeling while the resonances on PCB under very high frequency are being considered. Based on above steps, the SPICE compatible equivalent circuit can be established and be connected with other circuit model in the same pattern. In this way, the analysis of signal integrity for a complicated interconnecting system can be performed more efficiently