Accurate HSPICE modeling of arbitrary package geometries using transmission-line equivalent techniques

Arbitrary package geometries can be converted into accurate high-speed transmission line equivalent circuits using standard equations for characteristic impedance, plate capacitance, and unit delay, Constructing the correct transmission-line topology requires an understanding of how the skin effect alters high-speed electromagnetic field propagation within a microelectronic structure. Using such transmission-line techniques, this paper examines in detail the high-speed electrical behavior of a number of common package structures, including signal vias in singte-ended and differential stripline and microstrip configurations; single-ended and differential signal wires passing over gaps in microstrip or stripline reference planes; and single- and dual-reference stripline systems. These transmission line representations can be readily simulated with any HSPICE or equivalent circuit simulation engine. These techniques are then applied to the packages and hardware data presented in [1]. It is shown that the noise measurements of the package having the most severely compromised reference mesh and power-supply vias under the die are dominated by cavity noise.