High-Entropy Analog-Based Strong Physical Unclonable Function With Area-to-Entropy-Ratio of 166 F2/bit

Abstract—In this letter, we present a high-entropy strong Physically Unclonable Function (PUF) utilizing weak-inversion current mirrors implemented in a standard 65-nm CMOS technology. Each response bit of the proposed PUF relies on the threshold voltage differences of minimum-sized transistors arranged in a 32 × 32 matrix. The analog operating principle enables encoding at least three effective bits per transistor pair, significantly improving entropy density. Leveraging a bit-masking technique, the design achieves remarkable robustness, attaining a bit error rate (BER) as low as 0.22% even under substantial supply voltage and temperature variations, with less than 10% discarded bits. The presented architecture exhibits a record areato-entropy ratio of 166 F2/bit, confirming its suitability for highly secure, compact applications in hardware security.