Embedded systems: past experience and future demands

The development of mixed technologies, the technological progress that step by step moved the limits of CMOS transistors when used in analog applications, the demand for higher integration, increased reliability and lower system cost have recently led to the development of integrated circuits more complex and sophisticated. To meet these insatiable needs, combining analog and digital functions into a single chip has been an unavoidable path to follow. As a matter of fact, analog and digital real time signal processing is compatible now to a single chip solution. This integration, far for being a mere collage of already circuits and macros (in fact, if was until the early '80s that ICs vendors attempted commercial mixed-mode designs) asked the ICs design community to cultivate technologies where the analog and digital "incompatibilties" can, on the contrary, coexist. This paper, in the attempt to deal with the genesis and evolution of mixed-mode ICs wants, through practical examples, firstly to report about the increasing complexity of this kind of products (from a simple digital interface to DSPs and micros embedded together with analog functions) and secondly, to describe the obstacles (ranging from technology to CAD) still challenging the ICs designer and often hiding the real productivity of mixed-mode integrated circuits.