Effects of discontinuities (vias) on high speed interconnects

Vias and bends are commonly encountered as nonuniformities along traces of interconnect on high performance multichip modules. The extent of degradation of signal propagation characteristics due to the presence of discontinuities has been investigated by developing and using a simulator based on the transmission (ABCD) matrix parameters, which facilitates concatenation of many transmission line systems. The approach models the reactive energy stored in a discontinuity as a lumped tee-network using three dimensional parameter extractors. A case study on the thick film geometry of the IBM ES9000 module investigates the effects of vias on propagation delay time, signal distortion, characteristic impedance and additional noise generated due to reflections at the termination and at the source for different input rise times