Environmental-Variation-Tolerant magnetic tunnel junction-based physical unclonable function cell with auto write-back technique

Recently, with the increase in popularity of Internet of Things (IoT) devices, cryptographic protection techniques have become necessary for high-security applications. In general, IoT devices have strict power and area constraints. Thus, use of a physical unclonable function (PUF), which can generate a secret key at low cost, can be advantageous for high-security IoT devices. This paper presents a novel environmental-variation-tolerant (EVT) magnetic tunnel junction (MTJ)-based PUF that has a small area, high randomness, and low bit error rate (BER) compared to previous PUFs. The simulation results obtained using industry-compatible 65-nm model parameters indicate that the proposed PUF exhibits an inter-chip Hamming distance of 0.4901 and entropy of 0.9997, which proves the randomness of the PUF response. In addition, the proposed PUF exhibits the lowest BER across a wide voltage range (0.9 V-1.3 V) and temperature range (-25 °C - 75 °C) compared with previous PUFs.