Model engineering is an important activity within the design flow of in-
grated circuits and signal processing systems. This activity is not new
at all in computer engineering, however, and takes a central role in
practice. Model engineering of digital systems is based on agreed
concepts of abstraction - erarchies for design object representations as
well as the expressive power of hardware description languages (HDL).
Since their gradual introduction over time HDL have proved to form the
foundation of design methodologies and related design flows. Design
automation tools for simulation, synthesis, test generation, and, last
but not least, for formal proof purposes rely heavily on standardized
digital HDL such as Verilog and VHDL. In contrast to purely digital
systems there is an increasing need to design and implement integrated
systems which exploit more and more mixed-signal functional blocks such
as A/D and D/A converters or phase locked loops. Even purely analog
blocks celebrate their resurrection in integrated systems design because
of their unique efficiency when is comes to power consumption -
quirements, for example, or complexity limitations. Examples of such
analog signal processing functions are filtering or sensor signal
conditioning. In g- eral, analog and mixed-signal processing is
indispensable when interfacing the real world (i.e., analog signals) to
computers (i.e., digital data processing).