Self-Adaptive Write Circuit for Magnetic Tunneling Junction Memory With Voltage-Controlled Magnetic Anisotropy Effect

Currently, commercial semiconductor-based memories face the problem of static energy consumption caused by leakage currents. Magnetoelectric random access memory (MeRAM), as a type of nonvolatile memory, provides a solution to this problem and can be used to replace the entire memory hierarchy as a universal memory. In contrast to spin transfer torque RAM (STT-RAM), MeRAM uses voltage controlled magnetic anisotropy (VCMA) effect to manipulate the switching of magnetic tunnel junctions (MTJs). MeRAM or VCMA-MTJ technology is more energy efficient and less likely to break down than STT-RAM. However, VCMA-MTJ suffers from serious write problems caused by variations in the VCMA coefficient, the external in-plane magnetic field, and the CMOS process. In this paper, a compact and SPICE-compatible VCMA-MTJ model is proposed. Then, a self-adaptive write circuit is proposed in which the write process is robust to variations in the VCMA coefficient and the external inplane magnetic field. Finally, two practical methods are proposed to make our proposed self-adaptive write circuit also robust to 3 sigma CMOS process variations, as demonstrated by Monte Carlo simulations. The proposed self-adaptive write circuit can assist in the design of next-generation high-speed, low-power MeRAM chips.