An Invasive-Attack-Resistant PUF Based On Switched-Capacitor Circuit

An invasive-attack-resistant physical unclonable function (PUF) with strong reliability is presented. The mismatch of capacitor ratios in real fabrication is sampled by a switched-capacitor (SC) circuit and further amplified by a latch-styled sense amplifier. Transmission lines connected to the sampling capacitors are used to cover and protect the whole chip from outside invasive attacks. The proposed SC PUF is fabricated using HJ standard 0.18 μm CMOS process. Simulation results show that the invasive-attack-resistant sensitivity is less than 2.56 fF. The failed outside invasive attack efforts verify the anti-invasive-attack property of the PUF unit. Besides, measured results show that the proposed SC PUF circuit with 3 V/1.8 V-VDD achieves an error rate 1x-5.5x lower than other PUF implementations. An error correction block is also presented to achieve a nearly zero error rate. The measured average error rate, bias, average intra-die HD and average inter-die HD of the 3 V/1.8 V-VDD SC PUF with error correction block is 0%, 46.72%, 0%, and 49.84% respectively.