A Highly Reliable and Energy-Efficient Schmitt Trigger PUF Featuring Ultra-Wide Supply Voltage Range

Abstract

In this brief, we present a Schmitt trigger physical unclonable function (ST-PUF) featuring high reliability under ultra-low supply voltage. By replacing the standard complementary-metal-oxide-semiconductor (CMOS) inverter of traditional static random access memory (SRAM) PUFs to ST inverter, the relatively large transition width can be significantly reduced by 1.91~ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$121.8\times $ </tex-math></inline-formula> under different supply voltage and temperature (VT) conditions. This leads to dramatically enhanced reliability against the environmental noise and VT variations. The proposed implementation is validated using a 65-nm 1.2 V standard CMOS process, and the reference supply voltage is optimized to be 0.4 V, in order to strike an excellent balance between the power/energy consumption and the reliability. According to our extensive post-layout simulation results, the worst-case bit error rate (BER) is reported to be 2.14% with the supply voltage varying from 0.3 V to 0.5 V and the temperature varying from −40°C to 120°C. The core energy consumption is simulated to be 2.31 fJ/bit at a throughput of 160 Mb/s. Moreover, the generated raw PUF bits have passed both the National Institute of Standards and Technology (NIST) and auto-correlation function (ACF) randomness tests.