Automatic equivalent discrete distributed circuit generation for microstrip interconnection discontinuities

This paper presents a novel technique that allows one to derive so called discrete distributed networks for general microstrip interconnection discontinuities that are small compared to the wavelength. Our interest is in high speed digital circuits so the requested bandwidth is about 5 GHz. The basis of our technique is the classical MoM solution of an appropriate mixed potential integral equation, using a mesh of rectangles and triangles. However, instead of combining the current and charge couplings to a system impedance matrix, they are interpreted as an equivalent circuit, as in the PEEC-method, developed by Ruehli (1974). Then, energy principles are used to reduce this network. In this circuit reduction, no fitting procedure is needed, which has a serious impact on calculation time. Also, for design purposes, we have made our technique such that there exists a one to one correspondence between an element in the equivalent circuit, and some part of the physical structure. The paper is restricted to two-ports on pure microstrip substrates.