This work deals with the fundamentals of the so-called Ultra-Low-Power CMOS technology which aims to reduce the power consumption of future digital Very-Large-Scale Integrated (VLSI) circuits drastically in comparison to conventional CMOS technology. This is achieved by reducing the internal supply voltage of the integrated circuits to a minimum and by simultaneously decreasing the threshold voltages in order to maintain the required performance. Where this is not possible parallelization and so-called pipelining can be used to achieve the targeted system throughput even if the single transistors' speed is reduced in favor of a further reduction of the power consumption.
The reduction of the supply voltage as well as the small threshold voltages raise a series of problems in many areas of integrated-circuits technology. For example, the traditionally small upper bounds for the leakage currents are scrutinized. To hold on to the commonly used values, especially, the still high supply voltages, would mean a medium-term stop to the technology development. In this work the fundamentals of Ultra-Low-Power (ULP) technology are developed with analytical analyses and with computer aided methods covering also extreme ranges of technology and operating parameters.
Basic prerequisites for modern semiconductor technology development are appropriate numerical algorithms and tools which enable an efficient and reliable computer aided evaluation of new device structures and technologies. As many commonly used standard methods fail at the small voltages of well below one Volt, which is typical for an Ultra-Low-Power technology, a new and highly accurate device model for circuit simulation was developed in this work as well as a new method for performance metric of a device. Using the device model the functionality of various digital and analog circuits could be shown, and the performance metric enabled complex optimization tasks with a minimum effort of CPU time.
The introduction of a new technology affects not only digital circuits but also the area of analog and mixed analog digital circuits which often serve as an interface to the outside world and are integrated together with the digital part on the same chip. In this work it could be shown for the first time that important analog circuits can work even at supply voltages of one half volt and that analog-digital converters - the key component of mixed analog digital circuits - operating at 0.2V can still be realized.