A reliable physical unclonable function (PUF) for chip fingerprint using current starved delay element (CSDE) is described in this paper. The proposed PUF is composed of CSDE-based sensors

time difference amplifier

time difference comparator

voting mechanism and diffusion algorithm circuit. By capturing manufacturing process variations

each sensor produces two slightly different delay-time values that can be compared in order to create a digital identification (ID) for the chip. A new diffusion algorithm is designed to further improve the uniqueness of PUFs. Time difference amplifier and voting mechanism are introduced to simultaneously improve the reliability of PUFs across temperature and supply voltage variations. The proposed PUF is designed in 0.18μm CMOS technology. Simulated results show that the proposed PUF has a good output statistical characteristic of uniform distribution

and a high stability of 97.5% with respect to temperature variation from -40℃ to 100℃

and supply voltage variation from 1.7V to 1.9V.