A Multi-Threshold CMOS NULL Convention Logic asynchronous circuit (MTNCL). The MTNCL circuit provides delay-insensitive logic operation with significant leakage power and active energy reduction. The MTNCL circuit is also capable of functioning properly under extreme supply voltage scaling down to the sub-threshold region for further power reduction. Four MTNCL architectures and four MTNCL threshold gate designs offer an asynchronous logic design methodology for glitch-free, ultra-low power, and faster circuits without area overhead.