y, information is stored by modulating the properties of the waveforms that are transmitted, e.g. their amplitude and phase. Information is lost due to distortion of a waveform's shape as it travels from sender to receiver. These shape distortions are, for example, due to linear, nonlinear and stochastic building block behavior. Predicting them is of great importance in estimating the probability of transmission errors to occur (bit error rate). Hence our need for accurate building block models. 2.1 Models, modeling and analysis A major part of this text is about models, modeling and analysis. Before focusing on particular applications, it is useful to spend some time to clarify these concepts. 2.1 MODELS, MODELING AND ANALYSIS In what follows, "models", "good models", "modeling" and "analysis" are given a precise meaning. This provides the context for the methods presented in this text. We also stress the importance of having good models available to make top-down design truly possible. 2.1.1 Models: what you want or what you have Modeling and analysis is all about manipulating models. So, the first topic to be ad- dressed sounds: what is a model? Almost any introductory textbook on physics pro- vides a definition. A fairly thorough and consistent treatment on the matter can be found in [Hest87]. There, the author defines: Definition (Model-Physics): A model is a conceptual representation of a real object. The means used for representing an object can be quite general: it may involve a verbal description, a set of mathematical equations, a collection of measurement data or com- binations of the aforementioned. Note that for engineering purposes, the word "object" is often too general and abstract. It is often better to use "system" or "circuit" instead. From an engineering point of view, the definition above does not satisfy. It highlights the fact that physics is mainly concerned with description and analysis of systems (ob- jects) that exist. Engineers, on the other hand, are also concerned with the creation o