Design Space Exploration for Phase Transition Material-Augmented MRAMs With Separate Read-Write Paths

Shamiul Alam, William Mitchell Hunter, Nazmul Amin, Md. Mazharul Islam, Sumeet Kumar Gupta, Ahmedullah Aziz

Abstract: This report presents a design space analysis for the phase transition material (PTM)-augmented magnetic random-access memories (MRAMs) with separate read–write paths. PTM is augmented in parallel with the magnetic tunnel junction (MTJ), improving the read performance along with providing separate read–write paths. Compared to the standard MRAM, PTM-augmented design achieves up to $1.7 \times $ boost in cell tunnel magnetoresistance (CTMR), $1.2 \times $ increase in read disturb margin (RDM), and ${\sim }3.75 \times $ increase in sense margin (SM) at the cost of ${\sim }4.75 \times $ more power consumption. Here, we first discuss the operating region and biasing requirements to achieve performance improvement. Then, we thoroughly explore the design space to put more options on the table for choosing the material and device structure. Finally, we perform the variation analysis where we address the performance and variation immunity tradeoffs. We demonstrate a 1000-point Monte-Carlo analysis to illustrate the effects of process variations on the performance. With lower distinguishability and read stability, the variation tolerance of the design can be improved manifold employing device-circuit co-design methodology and vice versa.