behavior of high-Q harmonic oscillators. A general framework is presented to deal with this kind of behavior together with several examples. Chapter 6 (Conclusions), draws conclusions and provides directions for re- searchers who would like to further explore the tracks outlined in this text. Chapter 2 Modeling and analysis of telecom frontends: basic concepts You insist that there is something a machine cannot do. If you tell me pre- cisely what it is that a machine cannot do, then I can always make a machine which will do just that. -John von Neumann ood models and efficient methods for constructing and evaluating them are of ut- most importance in making true top-down design of telecom frontends a reality. This book intends to contribute to the work in this area. Firstly, however, we must clearly define "models", "good models", "modeling" and "analysis". You cannot re- alize something, e.g. a good model, if you cannot tell what it is you want to realize. Therefore, section 2.1 spends some time to elaborate these concepts. Incorporating all relevant prior knowledge and experience is one of the main properties that characterize good (telecom building block) models. It makes models reliable in a sense that their behavior can be trusted to correspond with that of physical implementa- tions. This is of great importance in avoiding redesigns. Furthermore, exploiting prior knowledge helps to improve, for example, simulation efficiency. It allows us to use "shortcuts" in capturing a system's behavior. As this book mainly deals with telecom frontends and their building blocks, section 2.2 reviews some typical telecom frontend architectures and summarizes our prior knowledge of their behavior. Further chapters will often exploit this knowledge to simplify analysis. In communications, the relevance of the different aspects of a building block's behav- ior -and therefore the need to incorporate them into (good) models- is measured by their impact on the system's overall performance in transmitting information. Phys- icall