Delay-insensitive asynchronous ALU for cryogenic temperature environments

This paper details the design and performance of a delay-insensitive asynchronous 8-bit ALU for an asynchronous 8051-compliant microcontroller intended for extreme environments. The ALU was designed using a quasi-delay-insensitive logic called NULL Convention Logic (NCL), in order to allow for reliable circuit operation over a wide temperature range and enable extreme supply voltage scaling for low power consumption. The ALU was fabricated along with several other 8051-essential components at MOSIS using the IBM SiGe5AM 0.5 mum process. A series of tests at both room and cryogenic temperatures has been performed, which has demonstrated that the designed ALU is able to operate correctly from 2K (-271degC) to 297K (23degC), as well as over wide supply voltage variations.