Bridging the gap between the digital and real worlds: the expanding role of analog interface technologies

The dramatic evolution of semiconductor technology over the last 50 years caused a real industrial and social revolution that is ongoing today. The progress from single-transistor to ULSI circuits has been very fast. As technology proceeded according to the well-known Moore's Law, circuit-design techniques moved more and more from analog to digital following the continuous progress made in microlithography. While there has been a corresponding huge increase in the computing power of digital circuits, this has not been accompanied by a comparable evolution in the capability of integrated circuits to interface to the external world. For free-standing computers, speed is the key factor. In other applications such as mobile phones, the interfaces with the external world are fundamental and provide the driving force in the evolution of these products. Technologies like BiCMOS, HVCMOS and BCD, which are already available and will further evolve in the future, appear to be more suitable than pure CMOS in satisfying those needs. We are moving now to SoC (System on Chip) and in the future to SiP (System in Package) techniques that will very likely include micromachined technologies. In this paper, both recent and future developments in analog interfaces will be analyzed, with particular attention given to the problem of power-consumption reduction in portable devices. As well, an overview of new applications of MEMS devices will be presented.