On the influence of vias on a PCB power-bus

Abstract

In this paper, a method for the investigation of the influence of a through-hole via on a printed circuit board power-bus is presented. Therefore based on an introduced via model for a through-hole via its scattering parameters are extracted using a de-embedding algorithm. After the following calculation of the via model elements with the two-port theory, the extracted impedances are inserted in a known formula for the power-bus impedance. In addition, it is shown how the signal return current acts as an excitation source of the waveguide modes within the power-bus.

Lumped models for Vias in multilayered PCBs

“…Both extraction methods, that will be explained here, depend on the Sparameters of the overall geometry from measurements or numerical simulations. The first method is based on a matrix de-embedding, where the behavior of the lines is eliminated from the overall data to extract the S-parameters of the via [9], [24] - [26]. After that, the via model elements can be extracted on two different ways.…”

“…After that, the via model elements can be extracted on two different ways. On the first way, the two-port theory is used to extract the elements of an assumed impedance via model directly from the via S-parameters [9], [25], [27]. In the second approach, the parameters of the lumped via model are determined by approximate calculations (subsection III-A).…”

“…5 the interactions between the via and the PB can be explained [9]. In addition to the passive via model, it includes the induced voltage on the via …”

Coupling between Vias and the PCB Power-Bus

“…5) can be extracted considering symmetry (Z 11 = Z 22 ) and reciprocity (Z 21 = Z 12 ) (Antonini, Scogna and Orlandi, 2002), (Heinrich and Dickmann, 2008):…”

“…In order to extract the S -parameters of the v ence of the lines must be de-embedded. This ca out with a matrix de-embedding using the scatte parameters (T -parameters) (Antonini, Scogna a 2003, 2004, (Heinrich and Dickmann, 2008) in ing steps:…”