A binary-search switched-current sensing scheme for 4-state MRAM

A current-mode binary-search sensing scheme for a 4-state one-transistor one-magnetic tunnel junction (1T1MTJ) magneto-resistive random access memory (MRAM) is proposed. By using the switched-current technique, it is able to read data non-destructively with a magneto-resistive (MR) ratio of as low as 5%. The circuit is designed using a 0.18μm CMOS process and the performance is verified by HSPICE. Compared to the parallel sensing approach, the proposed sensing scheme consumes less power and chip area and requires fewer comparison steps. Compared to the serial sensing approach, it allows a shorter read access time while requiring the same number of comparisons