Analogue behavioural modelling-at systems level

The majority of integrated circuits today fall into two classes, those which are primarily digital with a small amount of analogue support circuitry (Da) and those which are primarily analogue with digital elements (Ad). For the purposes of this article fully analogue designs are lumped in with Ad designs since the system level simulation problems are similar. Purely digital designs are not discussed because the systems level simulation of these is relatively simple. Abstraction of analogue circuit functions is considerably more complex than for digital circuits because characterisation of an analogue circuit is more complex. The vast diversity of analogue functions compounds the problem