An expression of high‐frequency characteristics on a high‐density multilayer wiring board using an LC ladder network as a unit segment

Abstract

SUMMARYThis paper presents a method of expressing a highspeed signal transmission line connecting the LSIs in a high-density multilayer wiring board in terms of cascaded connections of LC ladder networks. For signal transmission with a fundamental frequency beyond 1 GHz, the signal transmission lines in a multilayer board are treated as distributed transmission lines. However, there exist many scattering elements such as vias for interlayer connection in the multilayer board that disturb the transmission characteristic. Transmission characteristics affected by these elements are analyzed by electromagnetic field simulation in general. However, the simulation requires a lot of simulation time and computer resources. In order to simplify the simulation, the signal line structures in the board are constructed with combinations of several segments. Moreover, each unit segment is expressed in terms of an LC ladder network so that an analysis based on the lumped elements can be carried out within a short time. This paper describes a technique for deriving the L and C values of the ladder equivalent circuits for various unit segments such as passive components and transmission lines. By comparison with the electromagnetic field analysis and measurement, the usefulness of the method is demonstrated.