1Resistive Computation: A Critique

Abstract—Resistive Computation was suggested by [6] as an idea for tacking the power wall by replacing conventional CMOS logic with Magnetic Tunnel Junction (MTJ) based Look-Up Tables (LUTs). Spin Transfer Torque RAM (STTRAM) is an emerging CMOS-compatible non-volatile memory technology based on Magnetic Tunnel Junctions as a memory bit [3]. The principal advantage of STTRAM is that it is leakage-resistant, which is an important characteristic beyond the 45nm technology node, where leakage concerns are becoming a limiting factor in microprocessor performance. Although STTRAM is a good candidate for replacing SRAM for on-chip memory, we argue in this article MTJ-based LUTs are unnecessarily expensive in terms of area, power, and performance when implementing fixed combinational logic that does not require the reprogramming ability provided by MTJs. Index Terms—Resistive computation, magnetic-tunnel junctions, spin transfer torque RAM, MRAM, dynamic current-mode logic, leakage power.