Self-Timed Read and Write Operations in STT-MRAM

Spin-transfer torque magnetic random access memory (STT-MRAM) is a promising memory technology because of its advantageous features, such as nonvolatility, scalability, high density, zero-leakage, and CMOS compatibility. However, one of its major drawbacks is the high overall energy consumption. To make matters even worse, the write process in STT-MRAM is of stochastic nature, i.e., the completion of a write operation is nondeterministic. However, if the read/write completion could be detected on the fly (i.e., dynamically) and the respective components could be turned-OFF immediately, the energy consumption can be reduced by a large extent. Therefore, we propose a technique where the read and write completion signals are generated asynchronously on the fly using a self-timed bitwise technique. With this approach, the memory consumes power only when it is in the actual operational mode. Experimental results show that this technique significantly reduces the energy consumption of read and write operations with negligible area overhead.