TABLE OF CONTENTS Frequency modeling and noise analysis are very important when describing analog and mixed-signal systems. The ability to specify transfer functions in the frequency domain is also quite useful in modeling systems. In this chapter we look at the mechanisms provided by VHDL-AMS for modeling spectral and noise sources as well as for transfer functions in the frequency domain.
Although the discussions thus far in this book have focused on time-based modeling and simulation with VHDL-AMS, we can also represent frequency domain concepts in VHDL-AMS. In this chapter, we focus on modeling frequency-based views of a system and the interaction between time-based and frequency-based views. We start with small-signal frequency simulation to calculate the frequency response of a system over a range of frequencies. Next, we consider capabilities in VHDL-AMS for modeling noise. Finally, we discuss VHDL-AMS support for Laplace and Z transfer functions in the frequency domain.
As all engineering students learn during their undergraduate studies, frequency is an important aspect of a system's behavior. In electrical systems, we often see filters that pass or amplify certain frequency ranges and attenuate others. Mechanical systems often have resonant frequencies for oscillation. Control systems often employ feedback in which frequency-related issues are key aspects of the system behavior. Because the focus of this book is the VHDL-AMS language and its use, we will not discuss the area of signals and systems in detail. Readers seeking additional information on this area should seek out the standard texts used in junior-...
