Analog and Mixed-Signal Innovation: The Process-Circuit-System-Application Interaction

Innovation in analog and mixed-signal electronics becomes increasingly more important to the continued growth of the IC industry. Technologists working in the analog and mixed-signal arena certainly share, with their digital counterparts, the overarching goal of reducing power and cost-per-function in each IC generation. But they must also operate under physical constraints that, until recently, have been secondary in the digital world. From the advent of the first analog IC, analog designers have exploited the potential of the process technology to develop circuits that minimize the impact of variation in process parameters on product performance. The bandgap reference is just one example. More generally, trim, calibration, and circuit techniques such as charge-redistribution, enabled economic production of amplifiers and data converters with 12-bits (or better) precision on "8-bit" processes. In addition, while process scaling has enabled the development of a wide variety of products, from cell-phones to advanced medical-imaging systems, the success of these products depends in large measure on their ease of use, and seamless connection to wireless and wired networks. Analog and mixed-signal subsystems, including display drivers, and WLAN and cellular radios, support these critical interfaces. The downward scaling of supply voltage in deep-submicron CMOS (now at 1V), may limit dynamic range, forcing some analog functions to be implemented on other processes, but it has also enabled new circuit architectures that gain back dynamic range. The creative combination of process, design, and system architecture in providing robust solutions for demanding applications, will prove to be even more crucial in the future. Such solutions will be essential in meeting the challenges posed by the physical realities of deep-submicron design in achieving gigahertz speeds, minimizing power- consumption, and integrating multiple functions in smaller packages.