High-Speed Interconnect Modeling and High-Accuracy Simulation Using SPICE and Finite Element Methods

SPICE-based interconnection simulation is described for multiple coupled lines and for lines with three-dimensional discontinuities. Two- and three-dimensional finite element methods are presented for the quasi-TEM analysis of arbitrary interconnection structures. Partial capacitance and partial inductance values for three-dimensional discontinuities are obtained by defining input and output ports for the discontinuity and deembedding the two-dimensional regions to the plane of the discontinuity. This procedures is highly accurate and reliable and can be used to model arbitrary interconnect geometries. Interconnection circuits are entered via geometric CAD and are meshed and solved automatically by using adaptive mesh generation. Equivalent circuit models of typical 3D interconnects such as bends, vias, T junctions and chip packages are described. Simulations are based on model decomposition for multiple lines implemented using SPICE. We show that the quasi-TEM analysis and the full wave analysis of a T-junction are nearly identical up to 10 GHz.