Hybrid Multiplexing (HYM) for Read- and Area-Optimized MRAMs With Separate Read-Write Paths

We present a hybrid multiplexing (HYM) scheme for MRAMs with separate read-write paths, employing different bit-cell selection methods during read and write based on their suitability for data sensing and switching operations. The proposed technique allows the sharing of the read access transistor among the cells belonging to the same word, leading to area savings and enhancement in distinguishability. Furthermore, by employing dummy bits in an array and setting their values according to the process corner, the spread of the read current due to global variations can be tightened. We apply our technique on MRAM with spin Hall effect-based write and show that the HYM achieves 20% to 25% area reduction along with 2.4X improvement in cell TMR, 25% to 38% lower write power, and upto 50% increase in the read disturb margin compared to the standard multiplexing. The spread of the read current reduces by 38% to 53% by employing the dummy bits.