Electromagnetic modeling of high-speed high-frequency interconnects.

Abstract

This dissertation develops in detail an approach to a three-dimensional full-wave electromagnetic field simulator, namely the finite element method (FEM), and applies it to various high-speed high-frequency interconnects, ranging from a simple via hole to an entire K/Ka-band MMIC phase shifter package. This approach has several essential features: the utilization of tetrahedron-based edge basis functions rendering spurious-free solutions, a non-uniform structured mesh generator giving flexible modeling capabilities, and implementation of artificial absorbing layers helping to simulate open boundary problems. In addition, the FEM is fully parallelized on a distributed memory machine (the IBM SP2). Two different parallelization strategies are implemented, among which the task parallelization strategy provides linearly scalable performance improvement due to the minimal communication overhead among the processors. With all the above features, the parallelized FEM has been successfully applied to the characterization of planar/non-planar high frequency interconnects, hermetic transitions, and K/Ka-band MMIC packages. In particular, the undesirable internal package resonances and energy leakages in the MMIC package are identified, and furthermore, a few mechanisms for the suppression of the above phenomena are suggested, and these are supported by rigorous numerical data. The lumped equivalent circuits for the vertical via holes are utilized in the system level EM modeling to provide appropriate inductances and capacitances. In this dissertation, characterization of various high-frequency interconnects has been stressed as well as parametric study. Special attention is devoted to development of the system level electromagnetic modeling for high-speed digital circuits and packages. This system level modeling is achieved by combining the FEM and the well known circuit simulator, HSPICE. It is based on the so-called tiling processor, which generates equivalent circuits for PCBs and ICs, and then the circuit simulator is employed for time or frequency domain characterizations. The hybrid approach implemented in this study renders effective simulations in frequency as well as time domain for a given geometry. The detailed derivation and applications of the system level electromagnetic modeling tool are described. Its validity and accuracy are proved by modeling the INTEL P6 board and package containing eight layers of signal, power, and ground planes and hundreds of signal traces.