In-order pulsed charge recycling in off-chip data buses

Abstract

This paper presents in-order pulsed charge recycling to reduce energy consumption in an off-chip data bus. The proposed technique performs charge recycling by employing three different steps. At the beginning of an off-chip data bus transaction, i) connect all bus lines that are expected to fall to a common node, ii) connect, one at a time and for a fixed period of time, each of bus lines that are expected to rise to the same common node to enable charge recycling, and finally, iii) resume regular data bus transaction by enabling the tri-state buffers to complete the remaining charging (discharging) of the rising (falling) bus lines. Experimental results in Hspice show that the proposed technique achieves 17.4% average energy savings in a 32 bit-wide data bus implemented in a 0.13¼m technology with a 1.8V supply voltage.