Embedded MRAM Macro for eFlash Replacement

In this paper, we have presented 28-nm embedded 8Mb 64 I/O Spin-Transfer-Torque Magnetic RAM (STT-MRAM) Macro. Besides being the one of the world's first mass product solution for embedded Flash (eFlash) replacement for Internet-of-Things (IoT) chips, it is also serves as a comprehensive storage memory solution in high-end System-on-Chip (SoC). The read and write cycle times are 20ns. Thanks to process and temperature compensated reference concept, the Macro gives a non-fail read at Magnetic Tunnel Junction (MTJ) R P and R AP resistances variation up to 1sigma 8% and at weak Tunnel Magnetic Resistance (TMR) down to 150%. Macro operates in industrial temperature range. The integrated adaptive Read-and-Write biasing circuit improves MTJ endurance and optimizes the memory's power consumption by 20%. The presented STT-MRAM saves 15 to 40% of area, compared to the same process eFlash.