CHARACTERIZATION OF HIGH-FREQUENCY INTERCONNECTS USING FINITE-DIFFERENCE TIME-DOMAIN AND FINITE-ELEMENT METHODS

MIC and MMIC packages capable of good performance at frequencies as hi gh as 60 GHz need to have small volume, low weight, microstrip and/or coplanar waveguide (CPW) compatibility and exhibit negligible electric al interference with the rest of the circuit. In order to acquire some of these characteristics, special provisions need to be made during c ircuit layout and design, resulting in high-density packages. The desi gned circuits have a large number of interconnects which are printed o n electrically small surface areas and communicate through the substra te in a direct through-via fashion or electromagnetically through appr opriately etched apertures. In a circuit environment of this complexit y, parasitic effects such as radiation and cross talk are intensified, thus, making the vertical interconnection problem very critical. In t his paper, transitions using through-substrate vias are considered and analyzed both in the time and frequency domains using the Finite Diff erence Time Domain (FDTD) technique and the Finite Element Method (FEM ), respectively. The merits of each method in conjunction with accurac y, computational efficiency and versatility are discussed and results are compared showing excellent agreement. Specifically, a microstrip s hort-circuit, a microstrip ground pad, a CPW-to-microstrip through-via transition and a channelized CPW-to-microstrip transition are analyze d and their electrical performance is studied.