Circuit‐level design technique to mitigate impact of process, voltage and temperature variations in complementary metal‐oxide semiconductor full adder cells

Abstract

Modern digital circuits are facing aggressive technology and voltage scaling under emerging technology generations. This study proposes a circuit-level technique to mitigate the adverse effects of process, voltage and temperature (PVT) variations on the design metrics of full adder (FA) cells under such ultra-deep sub-micron technology nodes. The proposed FA cells exhibit improved variability because of the use of inverting low voltage Schmitt trigger sub-circuits incorporated in the designs in place of inverters. The proposed circuits have been designed to operate in the near-threshold region, which offers a trade-off between performance and power consumption. The comparative analysis based on Monte Carlo simulations in a SPICE environment, using the 16-nm complementary metal-oxide semiconductor predictive technology model, demonstrates that the proposed technique is capable of mitigating the impact of PVT variations on major design metrics such as power, delay and power-delay product in FA cells. This improvement is achieved at the expense of two extra transistors for every replaced inverter in the FA cell.