An efficient FDTD approach of modeling power-delivery-planes with SMT decoupling capacitors

Based on a two-dimensional (2D) finite-difference time-domain (FDTD method, an efficient numerical approach is proposed to model the power/ground planes characteristics with surface mount technology (SMT) capacitors above them. The parasitic inductance (or ESL) and resistance (or ESR) of the decoupling capacitors are both considered in series with the ideal capacitor in the modeling. By a proposed recursive updating formulation in the 2D-FDTD, the series RLC lump elements are implemented into one cell and are numerically embedded between power and ground planes. It will be shown that this approach not only keep good accuracy for predicting the power-bus behavior, but also significantly improve the computing efficiency compared with the 3D-FDTD method. The method is also applied to multi-layer structure by FDTD-SPICE method and illustrates its accuracy and efficiency.