A Strong Physical Unclonable Function Based on SAR ADC
Renpeng Tian, Lan Dai · 2024
In this paper, a strong physical unclonable function (PUF) study based on successive approximation register ADC (SAR ADC) is proposed based on SMIC 18nm CMOS process, which utilises the combination of capacitor array structure and SC PUF in SAR-ADC, shared capacitor array to reduce the chip area, and gate-voltage bootstrap switch as a sampling switch to reduce the SAR ADC power consumption. The mismatch generated in the capacitor array is sampled by the SC circuit and further amplified by a latch. By covering the entire chip with a metal transmission line connected to the sampling capacitors, the PUF is resistant to intrusive attacks. By combining the SAR ADC and the PUF, the circuit enables switching between the ADC and PUF functions. The SAR ADC has an effective bit count of 9.24 bits and a sampling frequency of 1 MHz. The PUF has an inter-chip Hamming distance within 0.46 to 0.52, with a uniqueness close to 50 per cent, and an intra-chip Hamming distance of less than 0.035, with a reliability of 97 per cent.