Reliability/redundancy trade-off evaluation for multiplexed architectures used to implement quantum dot based computing

Conference · Thu Jan 01 04:00:00 EST 2004

OSTI ID:977764

Bhaduri, D ^[1]; Shukla, S K ^[2]; Graham, P S ^[3]; Gokhale, M ^[4]

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1. Debayan
2. Sandeep K.
3. Paul S.
4. Maya

With the advent of nanocomputing, researchers have proposed Quantum Dot Cellular Automata (QCA) as one of the implementation technologies. The majority gate is one of the fundamental gates implementable with QCAs. Moreover, majority gates play an important role in defect-tolerant circuit implementations for nanotechnologies due to their use in redundancy mechanisms such as TMR, CTMR etc. Therefore, providing reliable implementation of majority logic using some redundancy mechanism is extremely important. This problem was addressed by von Neumann in 1956, in the form of 'majority multiplexing' and since then several analytical probabilistic models have been proposed to analyze majority multiplexing circuits. However, such analytical approaches are extremely challenging combinatorially and error prone. Also the previous analyses did not distinguish between permanent faults at the gates and transient faults due to noisy interconnects or noise effects on gates. In this paper, we provide explicit fault models for transient and permanent errors at the gates and noise effects at the interconnects. We model majority multiplexing in a probabilistic system description language, and use probabilistic model checking to analyze the effects of our fault models on the different reliability/redundancy trade-offs for majority multiplexing configurations. We also draw parallels with another fundamental logic gate multiplexing technique, namely NAND multiplexing. Tools and methodologies for analyzing redundant architectures that use majority gates will help logic designers to quickly evaluate the amount of redundancy needed to achieve a given level of reliability. VLSI designs at the nanoscale will utilize implementation fabrics prone to faults of permanent and transient nature, and the interconnects will be extensively affected by noise, hence the need for tools that can capture probabilistically quantified fault models and provide quick evaluation of the trade-offs. A comparative study of NAND multiplexing vs. majority multiplexing is also needed in case the designers are confronted with the choice to implement redundancy in either way. This paper provides models, methodologies and tools for these much needed analyses.

• Research Organization: Los Alamos National Laboratory
• Sponsoring Organization: DOE
• OSTI ID: 977764
• Report Number(s): LA-UR-04-4882
• Country of Publication: United States
• Language: English

Related Subjects

97 MATHEMATICS AND COMPUTING
99 GENERAL AND MISCELLANEOUS
COMPUTERS
ERRORS
EVALUATION
FAULT TOLERANT COMPUTERS
IMPLEMENTATION
MATHEMATICAL MODELS
QUANTUM DOTS
REDUNDANCY
RELIABILITY