Performance Bounds of Asynchronous Circuits with Mode-Based Conditional Behavior

Asynchronous circuits with conditional behavior often have distinct modes of operation each of which can be modeled as a marked graph with its own performance target. This paper derives performance bounds for such conditional circuits based on the cycle times of successively larger collections of these underlying modes. Our bounds prove the somewhat intuitive result that treating a conditional circuit as unconditional for slack matching guarantees the circuit performance requirement conservatively. We also prove the somewhat counter-intuitive result that the average cycle time of a conditional circuit may be worse than the weighted average of the cycle time of its underlying collection of modes. Finally, the paper outlines the potential application of these bounds to future improvements in slack matching of such conditional circuits.