Jason Miller, Staff Engineer, Sun Microsystems
Gustavo Blando, Engineer, Sun Microsystems
Cheryl Preston, Staff Engineer, Sun Microsystems
Jim DeLap, Applications Engineer, Ansoft Corp.
Istvan Novak, Staff Engineer, Sun Microsystems

Beyond the traditional components of conductive and dielectric losses, periodic discontinuities generate additional losses on interconnects. For instance, on printed circuit boards (PCBs) and packages, periodic discontinuities may come from perforated planes and loading from regularly arranged via fields under large packages and sockets. There is an increased slope of attenuation with frequency due to periodic losses, with deeper resonant dips at frequencies where the periodic structure constructively lines up reflections. The frequencies where the dips occur are lower if the propagation delay between subsequent discontinuities is longer. The depth of the dips depends on how severe the discontinuities are. This presentation will provide measured and simulated data of this extra loss mechanism, together with simulated studies on the influencing parameters.