A switched-current sensing architecture for a four-state per cell magnetic tunnel junction MRAM

A current-mode binary-search sensing scheme for a four-state per cell one-transistor one-magnetic tunnel junction magneto-resistive (MR) random access memory is proposed. By using the switched-current technique, it is able to read data nondestructively with a MR ratio as low as 5%. The sensing circuit is designed using a 0.18-/spl mu/m CMOS process and the performance is verified by HSPICE simulation. At a supply voltage of 1.8 V, the data can be accessed in 17.5 ns with a power consumption of 475.9 /spl mu/W. Compared to the parallel sensing approach, the proposed sensing scheme consumes less power and chip area, and requires fewer comparison steps. Compared to the conventional serial sensing approach, it allows a shorter read access time while performing the same number of comparisons.