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A reliable and compact physical unclonable function based on unstable bits recycling scheme

Physically unclonable functions (PUFs) facilitate many security applications such as secure key generation, device authentication, counterfeiting detection and prevention. This paper presents an area efficient PUF with high reliability. We exploit the process variation of a single load transistor for the current mirror working at the subthreshold region, which is converted to a unique digital signature of the chip. Different from the previous reliability enhancement technologies that discard the unstable bits, the proposed PUF is capable of labelling and recycling the unstable PUF bits, leading to significantly increased reliability. The simulation results based on 65 nm 1.2 V CMOS technology have validated the proposed design, which exhibits a reliability of 97.12% and a uniqueness of 50.06%, with the working temperature varying from −40 °C to 120 °C and the supply voltage's fluctuation equal to ±10%. Moreover, the power consumption of the core PUF is only 8.2 μW at a throughput of 80 Mb/s, which corresponds to 102.5 fJ per response bit.