One of the many challenges faced by engineers working with the present design scenario is to estimate the extent to which a signal, with significant high frequency content, is affected when it is routed on a printed circuit board. The printed circuit board routing will include the transition through the geometries like micro-strip or strip-line transmission lines, via transitions, and irregularities or asymmetries in the aforementioned geometries. One of these discontinuities, the via transition, results in the interaction of the signal on the via and the cavity (plane-pair) through which it passes. The via transition modeling will help characterize a block in the signal path. Section 1 explains the cavity model, and derives an expression for the impedance at a port in a rectangular cavity. The via to cavity connection, and the via capacitance calculation is explained. Then, five practical examples are used to show the model assembly in a circuit fashion, and the results are compared to the measurements. This modeling approach has been automated and integrated into the Multilayer Via Transition Tool, a tool that models all the common PCB geometries and provides the results as network parameters for the user defined ports. This tool is used for performance analysis and design optimization for the high speed PCBs. The tool includes a basic graphic user interface and an engine. Section 2 explains the design methodology for the provided graphic user interface. It explains interface design from the basic set of user inputs required by the engine to run. This section also talks about the difficulties in implementing the interface, and the required improvements for a professional tool --Abstract, page iii
