C-elements for hardened self-timed circuits
Résumé
Self-timed circuits are slope sensitive: when the voltage of one input or internal node changes too slowly, the interconnected logical blocks might loose their local one-to-one synchronization. This phenomenon often leads to unwanted global dead-locks of the entire circuit. The deep-submicronic manufacturing process mismatches might create such situations where one logical block is significantly slower than the others. We applied two known solutions for ensuring the correct C-element behavior whatever the slopes are: the transistors are resized and the supply voltage is reduced in order to guarantee the overall chip correctness taking into account the process variations.