In the earlier chapters of this book, we have introduced and examined the structure and operation of fundamental building blocks, or essential components, of high-frequency integrated circuits. The emphasis has been on transistor-level operation, the influence of device characteristics and parasitic effects, as well as the input output behavior in time and frequency domains with the intention to fill the gap between fundamental electronic circuits textbooks and more advanced RF IC design textbooks that mainly focus on the state-of-the-art. In this chapter, we will address a different domain and consider various aspects of bringing together an entire system , especially for interfacing high-frequency analog components with corresponding digital processing blocks, using data converters. Instead of considering specific system architectures, the main aspects of system design will be presented with a generic approach in the following, as much as possible. The main philosophy is very similar to that of the earlier chapters: discussing design-oriented strategies and drawing attention to key issues that must be taken into account when combining analog and digital building blocks. For a detailed discussion of the system components and their circuit-level realizations, the reader is advised to consult any one of the excellent texts that already exist in this domain. ^[1]