This volume of Analog Circuit Design concentrates on three topics: (X)DSL and other communication systems; RF MOST models; and integrated filters and oscillators. The book comprises five chapters on the first topic with six each on the other two, all written by internationally recognized experts. They are tutorial in nature and together make a substantial contribution to improving the design of analog circuits. The book is divided into three parts: Part I: (X)DSL and other Communication Systems presents some examples of recent improved modem techniques which have resulted in much higher transmission speeds over the local telephone network. It also presents components for the implementation of different standards. Part II: RF MOST Models investigates the state of the art in RF MOST models. It compares the existing BSIM3v3, Philips' Model 9 and the EKV model with respect to their capability to accurately predict GHz performance with submicron CMOST technologies. It shows how it has now become quite feasible to model a MOST at very high frequencies, giving rise to an increased use of MOST technologies in RF applications. Part III: Integrated Filters and Oscillators illustrates how the increasing use of communication tools goes hand-in-hand with the design of analog filters and oscillators with greater flexibility and higher bandwidth.