A true random number generator based on perpendicularly magnetized voltagecontrolled\nmagnetic tunnel junction devices (MRNG) is presented. Unlike MTJs used\nin memory applications where a stable bit is needed to store information, in this\nwork, the MTJ is intentionally designed with small perpendicular magnetic anisotropy\n(PMA). This allows one to take advantage of the thermally activated fluctuations\nof its free layer as a stochastic noise source. Furthermore, we take advantage of\nthe voltage dependence of anisotropy to temporarily change the MTJ state into an\nunstable state when a voltage is applied. Since the MTJ has two energetically stable\nstates, the final state is randomly chosen by thermal fluctuation. The voltage controlled\nmagnetic anisotropy (VCMA) effect is used to generate the metastable state\nof the MTJ by lowering its energy barrier. The proposed MRNG achieves a high\nthroughput (32 Gbps) by implementing a 64 Ã?â?? 64 MTJ array into CMOS circuits and\nexecuting operations in a parallel manner. Furthermore, the circuit consumes very low\nenergy to generate a random bit (31.5 fJ/bit) due to the high energy efficiency of the\nvoltage-controlled MTJ switching.
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