Avoiding Unnecessary Write Operations in STT-MRAM for Low Power Implementation

Abstract—Spin Transfer Torque (STT) is a promising emerging memory technology because of its various advantages such as non-volatility, high density, virtually infinite endurance, scalability and CMOS compatibility. Despite all these features, high write current is still a challenge for its widespread use. When writing a value that is already stored, a significant current flows through the Magnetic Tunnel Junction (MTJ) cell which is almost the same as that required to flip the stored data. This increases the total power consumption of the memory. To address this issue, we propose a technique which can avoid unnecessary write operations with bit-level granularity. Our technique can save 68.9 % of the total write power consumption with a minor area overhead (0.68 %) and only a small timing penalty (1.33 %). Keywords—STT-MRAM, non-volatile memory, low power, write avoidance I