Hybrid NEMS-CMOS Architectures for Ultra Low Power Smart Systems: Architectures for Ultra Low Power Smart Systems

The availability of inexpensive and powerful processors provides the means for the computation ecosystem to change its fundamental paradigm towards the Internet of Things (IoT) where ubiquitous nanosystems add intelligence to every object that surrounds us. The new trend for most of those systems is to autonomously operate into a “zero-power” regime, i.e., manage their energy budget in such a way that they can provide the required functionality without any service until they become obsolete. Considering that these systems are most of the time inactive, the static power is the dominant power consumption component, thus the most effective way to fulfill the “zero-power” operation requirement is to diminish the energy consumption into the so called sleep/idle mode. The semiconductor community has been addressing the static power reduction issue at device level, but for the CMOS technology the effectiveness of such approach is limited by the interdependence between static power consumption and device performance. In view of this observation this thesis focuses on improving the energy efficiency of electronic products, battery-powered, and autonomous ones by making use of emerging leakage proof technologies in conjunction with the versatile CMOS counterpart. First, we performed a design space exploration to identify the most promising NEMFET geometries and to evaluate their potential performance in terms of switching delay, current capability, and leakage. Moreover we compared those parameters of interest with the ones offered by traditional transistors utilized in up to date CMOS technologies. Second, we assessed the NEMFET potential when utilized as sleep transistor in circuits featuring 2D cell based power gating, and find out if NEMFETs constitute a viable alternative to High - VTH FETs in sleep mode circuits. Furthermore, we proposed a novel 3D power management approach that attempts to alleviate issues associated with the NEMS utilization as sleep transistor in CMOS power gated integrated circuits. Given the two designs, we evaluated the 2D and 3D NEMFET based power management implementations energy efficiency when embedded into a computation platform executing a bio-medical sensing application. Third, we introduced a NEMFET based logic family tailored to the implementation of ultra-low energy functional units and processors. Fourth, we proposed a memory cell that relies on a NEMFET based inverter designed in such a way that no short circuit current can occur. Finally, we proposed and evaluated the “zero-energy” operation scenario potential of an improved version of the 3D-Stacked NEMS based power management architecture.