MTCMOS with outer feedback (MTOF) flip-flops

Multi-Threshold CMOS (MTCMOS) circuits combine high performance during active mode with low leakage during sleep, but have a fundamental difficulty when trying to keep the state during sleep mode. We propose several novel master-slave MTCMOS flip-flops which use an outer feedback connection in order to maintain state. These MTCMOS with Outer Feedback (MTOF) flip-flops are fast since they use only low threshold transistors on the forward (critical) path and minimum extra load. The area overhead is low since the outer feedback is simple and transistors not on the critical path can have high threshold and be reused for maintaining the state during sleep. A 100nm predictive technology with power supply ranging from 0.8V to 1.2V is used for verifying the circuits performance through simulation.