Miniaturization and portable devices have reshaped the electronic device landscape, emphasizing the importance of high performance while maintaining energy efficiency to ensure long battery life. FinFET and Tunnel-FET technologies have emerged as attractive alternatives to overcome the limitations of supply voltage scaling for ultra-low power applications. This work compares the performance of 10 nm FinFET- and TFET-based digital circuits from basic logic gates up to an 8k gates low-power microprocessor. When compared with their FinFET-based counterparts, the TFET-based logic gates have lower leakage power when operated below 300 mV, show higher input capacitance, and exhibit a reduced propagation delay under different fan-in and fan-out conditions. Our comparative study was extended to the synthesis of an MSP-430 microprocessor through standard cell libraries built particularly for this work. It is demonstrated that the TFET-based synthesized circuits operating at ultra-low voltages achieve a higher performance in terms of speed at the cost of increased power consumption. When the speed requirements are relaxed, the TFET-based designs are the most energy-efficient alternative. It is concluded that the TFET is an optimal solution for ultra-low voltage design.

This paper presents a 1024-bit self-adaptive memory address decoder based on Dual Mode Logic (DML) design style to allow working in two modes of operation (i.e., dynamic for high-performance and static for energy-saving). The main novelty of this work relies on the design of a controlling mechanism that mixes both of these modes of operation to simultaneously benefit from their inherent advantages. When performance is the primary target, the mixed operating mode is enabled, and the self-adjustment mechanism identifies at run time the logic gates that have to work in the energy-efficient mode (i.e., static mode), while those belonging to the critical path operate in the faster dynamic mode. Moreover, our address decoder can run in the fully static mode for the lowest energy consumption when speed is not a primary concern. A 65 nm CMOS technology was exploited to simulate and compare our solution with other logically equivalent dynamic and static designs. Operated in the mixed mode, the proposed circuit exhibits negligible speed reduction (8.7%) in comparison with a dynamic logic based design while presenting significantly reduced energy consumption (28%). On the contrary, further energy is saved (29%) with respect to conventional logic styles when our design runs in its energy efficient mode.

The trade-offs of the Tunnel-FETs (TFETs) in terms of delay, energy per cycle, and noise margin are compared with 10 nm FinFETs for a wide voltage supply ranging from 200 to 600 mV with a specific focus on the ultra-low voltage domain. A calibration process is carried out to ensure the same off-current and extrinsic capacitance in both devices. The TFETs presented a high advantage in terms of delay as well as a penalty in energy consumed. As a result, the TFET circuits show a better Energy-Delay trade-off in voltages as low as 350 m V. This is explained by a larger capacitance caused by the nature of the intrinsic materials chosen of the device modelling.