Charge Recycling in Power-Gated CMOS Circuits

Abstract--Design of a suitable power gating (e.g., multithreshold CMOS or super cutoff CMOS) structure is an important and challenging task in sub-90nm VLSI circuits where leakage currents are significant. In designs where the mode transitions are frequent, a significant amount of energy is consumed to turn on or off the power gating structure. It is thus desirable to develop a power gating solution that minimizes the energy consumed during mode transitions. This paper presents such a solution by recycling charge between the virtual power and ground rails immediately after entering the sleep mode and just before wakeup. The proposed method can save up to 43% of the dynamic energy wasted during mode transition while maintaining the wake up time of the original circuit. It also reduces the peak negative voltage value and the settling time of the ground bounce.

• Type: Journal
• Year: 2008
• Where: TCAD
• Authors: Ehsan Pakbaznia, Farzan Fallah, Massoud Pedram
• Keywords: Gating, Mode Transition, Super Cutoff Cmos, TCAD 2008