A 0.38-V operating STT-MRAM with process variation tolerant sense amplifier

This paper exhibits a 65-nm 8-Mb spin transfer torque magnetoresistance random access memory (STT-MRAM) operating at a single supply voltage with a process-variation tolerant sense amplifier. The proposed sense amplifier comprises a boosted-gate nMOS and negative-resistance pMOSes as loads, which maximizes the readout margin in any process corner. The STT-MRAM achieves a cycle time of 1.9 μs (= 0.526 MHz) at 0.38 V. The operating power is 6.15 μW at that voltage. The minimum energy per access is 3.89 pJ/bit when the supply voltage is 0.44 V. The proposed STT-MRAM operates at lower energy than SRAM when a utilization of a memory bandwidth is 14% or less.