A Physically Unclonable Function Based on Low-Power SAR ADC
Bingxu Liu, Jiaming Bao · 2024
A highly reliable physical unclonable function (PUF) circuit based on a successive approximation register analog-to-digital converter (SAR ADC) is proposed. The circuit combines SAR ADC and switched-capacitor PUF and can operate in either SAR ADC mode or PUF mode. The capacitor array in the SAR ADC is shared to save chip area overhead and increase the security of IoT devices. The SAR ADC is designed for low power consumption, and its corresponding algorithm has been redesigned. This paper presents a digital out-of-phase calibration comparator designed to reduce the offset of the comparator, which aims to increase the uniqueness and reliability of the PUF. The SAR ADC has an effective bit count of 9.42 bits at a sampling rate of 1 MHz, consuming 26.8 uW. The PUF's inter-chip Hamming distance ranges from 0.45 to 0.52, with a uniqueness of 48%, and the intra-chip Hamming distance is less than 0.03, with a reliability of 97%.