Models for integrated components coupled with their EM environment
Purpose - The main aim of this study is the modelling of the interaction of on-chip components with their electromagnetic environment. Design/methodology/approach - The integrated circuit is decomposed in passive and active components interconnected by means of terminals and connectors which represent intentional and parasitic couplings of a capacitive and inductive nature. Reduced order models are extracted independently for each component. Findings - The paper shows that one of the main theoretical problems encountered in the modelling of RF components is the difficulty to define a unique terminal voltage, independent of the integration path (this independence being a condition to allow the connection of the component in an electric circuit, where the voltage does not depend of the path shape). The concept of an electromagnetic circuit element that allows the interconnection between IC models is proposed as a solution for this drawback. The system is described either with EM field models, or by electric/magnetic circuits. By using the new concept of hooks, the EM interaction is described effectively with a reduced number of quantities. Research limitations/implications - Since hooks have a virtual character, their identification is the result of an optimization procedure. By increasing their number the model accuracy is improved as also is the computational effort. The optimal automatic identification of electric and magnetic hooks is the subject of further research. Currently, the hooks are placed manually. Practical implications - The modelling of IC components with hooks is part of a new methodology that takes a layout description of typical RF functional blocks that will operate at RF frequencies up to 60 GHz and transform them into sufficiently accurate, reliable electrical simulation models, taking EM coupling and variability into account. This will decrease extra design iterations, over-dimensioning or complete failures in the design cycle of RF-IC. Originality/value - For the first time, the concept of magnetic terminals is used to describe interactions in RF integrated circuits. These EM "hooks" are defined in mathematical terms, as proper boundary conditions. The concept of hooks is also new. The proposed modeling methodology for EM coupling is also new. The paper is useful for nEDA designers.
electromagnetism design circuits