Comparison Between a Full-Wave and a Quasi-Static Analysis for High-Frequency Interconnects Crossover in Multilayered Dielectric Media

Abstract

Microstrip discontinuities such as open ends, gaps, steps, bends, T junctions and crossing, which are fundamental passive components m microwave ad millimeter-wave monolithic circuits, have been extensively analysed by several authors.-For multilevel integrated circuits, what kInd of new typical transitions occur? We find, naturally, via holes and crossover between conducting strips. To date little has been reported on the exact analysis of such complex structures. Our object is to study a strip crossover in a multilayered dielectric media.Although the full-wave analysis provides the highest-degree of accuracy, it requires extensrve analytical and umerical calculations. In comparison, the quasi-static aanalysis are tradionally faster in term of CPU time and analytical process than ful-wave techniques. The choice ofa faster numerical tool (a quasi-static model) needs to define the range ofvalidity. This leads to develop a fiul-wave and a quasi-static analysis. That was done and we show for a typical structure the discrepancy versus frequency. MODELIZATION:The cross sectional and top views of the strip crossover, are depicted in Fig.l. Both strs are infinite length, perfectly conducting and mfinitely thi. Quasi-static analysis:Our study is based on electrostatic techniques. The crossover discontinuity can be characterized by the equivalent circuit represented Fig.2. To obtain the capacitances C1, C2, Cm by the excess charge technique, we adopt the formulation presented in [1], based on the Space Domai Integral Equation (SDIE). On account of multilayered media, the complex image theory [2] is applied to obtain an identical mathematical formulation for the electrostatic three-dimensional Green's function and an acceptable cdmputation time whatever the number of layers. With the equivalent circuit presented Fig.2, we can obtain the normalized impedance matrix and consequently the scattering matrix 1271