Electromagnetic modeling methodologies and design challenges of packages for 6.4-12.8 Gbps chip-to-chip interconnects

In order to predict and optimize the performance of high-speed digital systems, it Is essential to accurately model the interconnect systems. The traditional method of analyzing interconnects by decomposing the structure into subsections and representing them by circuit parameters calculated using quasistatic electromagnetic solvers loses accuracy at higher frequencies. Instead, it becomes increasingly important to use parameters obtained from full-wave analyses to determine the degradation of the interconnect performance due to 3D package structures. In this paper, the impact of packages on system performance is first discussed. Then, the unique design and modeling requirements and challenges for high-speed digital packages are described. This is followed by discussions on selection criteria of electromagnetic solvers and modeling methodologies. Several examples are presented to illustrate the success and limitations of the commercially available electromagnetic solvers. Future requirements of electromagnetic modeling for high-speed digital systems are also presented.