NAND-Structured Physically Unclonable Function With Current Mirror Switching Stabilization and Minimized CRP Discards

Abstract

This paper presents a NAND-structured physically unclonable function (PUF) incorporating a novel current mirror-switching stabilization scheme. The proposed design leverages sub-threshold current mismatches induced by process variations to generate random responses. To address scenarios where the current difference is insufficient for stable response generation, the current mirror-switching method amplifies the mismatch, thereby enhancing stability and reducing the number of discarded challenge-response pairs (CRPs) through trimming. Simulation results demonstrate that the proposed PUF achieves the worst-case bit flip ratio (BFR) 0.99% at 1.8 V and 80 ${}^{\circ }C$ with 1.64% trimming ratio. By applying the proposed current mirror switching method, the trimming ratio is reduced by 86.2% while maintaining equivalent reliability. Furthermore, the proposed PUF achieves robust BFR performance, with variations of 0.099% per 10 ${}^{\circ }C$ and 0.071% per 100 mV under temperature and supply voltage changes, respectively.