Near-Threshold 40nm Supply Feedback C-Element

Idan Schwartz1,  Adam Teman1,  Rostislav (Reuven) Dobkin2,  Alexander Fish1

1Low Power Circuits & Systems Lab, The VLSI Systems Center, Ben-Gurion University of The Negev, 2vSync Circuits Ltd


The growing demand for ultra low power applications has drawn interest in low voltage digital circuits, operating in the near-threshold region. Asynchronous circuits, operating with near-threshold supply voltages, are more attractive than their synchronous counterparts due to higher resilience to PVT variations. This paper presents a novel ultra-low power C-element, which is a basic building block in common asynchronous circuits. The proposed C-element is based on a Supply Feedback concept, implemented in a cross-coupled inverter latch. Utilization of this concept enables functionality under local and global variations down to 0.3V. The cell was designed using a standard low-power 40nm technology. Simulation results show a 5.8X-24X leakage reduction at 300mV as compared to a conventional Weak Feedback C-element operating at its minimal V_DD. Monte Carlo simulations prove that the proposed cell remains fully functional under global and local process variations.