FinFET Variability and Nearthreshold operation: Impact on Full Adders design using XOR Blocks Near threshold operation reaches good results to energy critical applications. However, it introduces a considerable degradation on delay. Moreover, considering nanoeffects, circuits operating at nearthreshold are more sensitive to process variability. This paper analysis 9 full adders built with internal blocks that contain different combinations of 3 XOR logic circuits operating with nominal and nearthreshold voltages under process variability effects. The experiments adopt the 7nm FinFET ASAP technology. The nearthreshold operation can reduce on 97% the maximum power consumption and 65% the total energy, with an impact of about 10 times on delay. Considering process variability impact on energy and delay, the nearthreshold operation turns the circuits about 1.6 and 4 times more sensitive in the critical cases, respectively. Compared with traditional full adders, the proposed circuits can improve around 15% of the delay with similar power results. The results provide valuable data and show how the impact of variability and nearthreshold operation are important factors that must be analyzed to design more robust and low power circuits.

Exploring Schmitt Trigger Circuits for Process Variability Mitigation Process variability has become one of the major factors concerning variations in IC metrics, such as performance and energy consumption, due to the aggressive technology and voltage scaling. This work analyzes the impact on the variability robustness of a Schmitt Triggerbased technique. Several works point out that the considered technique helps to improve the variability robustness at the electrical level. The technique was applied on four Full Adder considering two different Schmitt Triggers designs at the layout level using the 7nm FinFET technology node from ASAP7. Performance, energy, and area are taken into account. Results show, on average, up to 36% and 45% improvement in delay and energy variability robustness, respectively.