A Novel Group-Division-Multiplexing Complementary Symmetric Reference Sensing Scheme for MRAM

Emerging magnetic random access memory (MRAM) have shown huge potential for in-memory-processing and neuromorphic computing due to their attractive characteristics, such as non-volatility, low power consumption, high endurance and CMOS compatibility. In MRAM, the most commonly used scheme of reference signal for Sense Amplifier is adding corresponding reference cells to reduce the parasitic mismatch, which greatly improve the sensing margin. Obviously, the added reference cells not only consume additional area but also introduce extra parasitic capacitances to bit line, causing redundant power dissipation and access latency. This brief proposes a novel group-division-multiplexing complementary symmetric reference (GDM-CSR) sensing scheme without read disturbance, parasitic mismatch and regularity problem. The main feature of the sensing scheme is that all memory cells are divided equally into two groups with only two crossed reference cells, forming a simple complementary symmetric structure with high speed in operation and high efficiency in energy. Compared with the conventional structure of 256 bits VGSOT-MRAM, evaluation results show that the proposed GDM-CSR scheme achieves a short read delay (1.3ns), low power consumption (45.86 fJ/bit for read operation), and 9.66E-6 bit-error-rate (BER).