Low-power and testable circuit synthesis using Shannon decomposition
Structural transformation of a design to enhance its testability while satisfying design constraints on power and performance can result in improved test cost and test confidence. In this article, we analyze the testability in a new style of logic design based on Shannon's decomposition and supply gating. We observe that the tree structure of a logic circuit due to Shannon's decomposition makes it intrinsically more testable than a conventionally synthesized circuit, while at the same time providing an improvement in active power. We have analyzed four different aspects of the testability of a circuit: a) IDDQ test sensitivity, b) test power during scan-based testing, c) test length (for both ATPG-generated deterministic and random patterns), and d) noise immunity. Simulation results on a set of MCNC benchmarks show promising results on all these aspects (an average improvement of 94% in IDDQ sensitivity, 50% in test power, 19% (21%) in test length for deterministic (random) patterns, and 50% in coupling noise immunity). We have also demonstrated that the new logic structure can improve parametric yield (6% on average) of a circuit under process variations when considering a bound on circuit leakage.
design iddq test power noise immunity design-for-test dynamic supply gating shannon expansion test coverage