Low power microelectronics: retrospect and prospect

The era of low power microelectronics began with the invention of the transistor in the late 1940´s and came of age with the invention of the integrated circuit in the late 1950´s. Historically, the most demanding applications of low power microelectronics have been battery operated products such as wrist watches, hearing aids, implantable cardiac pacemakers, pocket calculators, pagers, cellular telephones and prospectively the hand-held multi-media terminal However, in the early 1990´s low power microelectronics rapidly evolved from a substantial tributary to the mainstream of microelectronics. The principal reasons for this transformation were the increasing packing density of transistors and increasing clock frequencies of CMOS microchips pushing heat removal and power distribution to the forefront of the problems confronting the advance of microelectronics. The distinctive thesis of this discussion is that future opportunities for low power gigascale integration (GSI) will be governed by a hierarchy of theoretical and practical limits whose levels can be codified as: (1) fundamental, (2) material, (3) device, (4) circuit, and (5) system