Increasing dynamic variability with technology scaling has made it essential to incorporate large design-time timing margins to ensure yield and reliable operation. Online techniques for timing error resilience help recover timing margins, improving performance and/or power consumption. This paper presents TIMBER, a technique for online timing error resilience that masks timing errors by borrowing time from successive pipeline stages. TIMBER-based error masking can recover timing margins without instruction replay or roll-back support. Two sequential circuit elements -TIM-BER flip-flop and TIMBER latch -that implement error masking based on time-borrowing are described. Both circuit elements are validated using corner-case circuit simulations, and the overhead and trade-offs of TIMBER-based error masking are evaluated on an industrial processor.

Bi-decomposition techniques have been known to significantly reduce area, delay, and power during logic synthesis since they can explore multi-level and, or, and xor decompositions in a scalable technology-independent manner. The complexity of bi-decomposition techniques is in achieving a good variable partition for the given logic function. State-of-the-art techniques use heuristics and/or brute-force enumeration for variable partitioning, which results in sub-optimal results and/or poor scalability with function complexity. This paper describes a fast, scalable algorithm for obtaining provably optimum variable partitions for bi-decomposition of Boolean functions by constructing an undirected graph called the blocking edge graph (BEG). To the best of our knowledge, this is the first algorithm that demonstrates a systematic approach to derive disjoint and overlapping variable partitions for bi-decomposition. Since a BEG has only one vertex per input, our technique scales to Boolean functions with hundreds of inputs. Results indicate that on average, BEG-based bi-decomposition reduces the number of logic levels (mapped delay) of 16 benchmark circuits by 60%, 34%, 45%, and 30% (20%, 19%, 16% and 20%) over the best results of state-ofthe-art tools FBDD, SIS, ABC, and an industry-standard synthesizer, respectively.

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Reliability of logic circuits is emerging as an important concern that may limit the benefits of continued scaling of process technology and the emergence of future technology alternatives. Reliability analysis of logic circuits is N P-hard because of the exponential number of inputs, combinations and correlations in gate failures, and their propagation and interaction at multiple primary outputs. By coupling probability theory with concepts from testing and logic synthesis, this paper presents accurate and scalable algorithms for reliability analysis of logic circuits. Simulation results for several benchmark circuits demonstrate the accuracy, performance, and potential applications of the proposed analysis technique.

There is a growing concern about timing errors resulting from design marginalities and the effects of circuit aging on speed-paths in logic circuits. This paper presents a low overhead solution for masking timing errors on speed-paths in logic circuits. Error masking at the outputs of a logic circuit is achieved by synthesis of a nonintrusive error-masking circuit that has at least 20% timing slack over the original logic circuit. The error-masking circuit can also be used to collect runtime information when the speed-paths are exercised to (i) predict the onset of wearout and (ii) assist in in-system silicon debug. Simulation results for several benchmark circuits and modules from the OpenSPARC T1 processor are presented to illustrate the effectiveness of the proposed solution. 100% masking of timing errors on all speed-paths within 10% of the critical path delay is achieved for all circuits with an average area (power) overhead of 16% (18%).