Improved impedance calculation of populated PCB power-bus structures

The impact of any number of lumped elements connected to the power-bus has been taken into account recently by using a modified modal summation. The formulas derived provide excellent results for calculating the power-bus impedance in the case of small admittances connected to the PCB. In the case of very large admittances, some errors in the calculations can be observed. In this paper, we further improve these formulas. The improved equations show a good agreement with the circuit theory even in the case of very large admittances connected to the PCB