A 28nm 512Kb adjacent 2T2R RRAM PUF with interleaved cell mirroring and self-adaptive splitting for extremely low bit error rate of cryptographic key
Xiaoyong Xue, Jianguo Yang, Yuejun Zhang, Mingyu Wang, Hangbing Lv, Xiaoyang Zeng, Ming Liu · 2019
Reliability and cost efficiency are of utmost importance for cryptographic key generation and storage in IoT applications. This paper presents a 2T2R RRAM PUF scheme with assisting circuit techniques for dense and reliable cryptographic key generation in 28nm logic process. The set time mismatch in two adjacent RRAM devices is exploited for PUF output with better tolerance against PVTA variations. Array architecture featuring interleaved cell mirroring improves the randomness by eliminating the systematic deviation. Self-adaptive splitting with current limiter eliminates the negative effect of mismatch in the peripheral circuits and suppresses the undue duration of large operation current. Silicon data demonstrates our RRAM PUF passes NIST test with intrachip Hamming distance (HD) of 0, inter-chip HD of 0.496 and bit error rate of-5@0-120 °C. The cell size of 2T2R PUF is 0.54 μm2and can be reduced when the selector is shared or the RRAM set/reset voltages are optimized below the core supply voltage.