LAUSR

In this paper, a concept of chip-package-board (CPB) interactive physically unclonable function (PUF) is presented as a physical countermeasure against malicious counterfeiting at not only chip fabrication but also at package/board assembly stages. A fully CMOS compatible coupled chaos oscillator with inductive wireless interaction incorporates assembly variations into PUF identification (ID) generations without any additional process/assembly options. Chaos is essentially not a random phenomenon but a deterministic non-periodic flow which can be utilized to extract reproducible ID. The strong parametric sensitivity of the chaos guarantees ID variety and unclonability over unpredictable process/assembly variations. An undesirable disturbance due to dynamic parametric fluctuations can be removed by phase-locked loop (PLL)-based replica feedback compensation together with mixed-signal post-processing for stable ID reproduction. The proposed CPB interactive PUF is silicon prototyped in 0.18- $\mu \text{m}$ CMOS for the proof of the concept. Eight samples of a compact 3150 $\mu \text{m}^{2}$ PUF successfully reproduce 512-bit unique IDs with <2.5% bit error rate (BER) before and after assembly. This for the first time demonstrates a potential capability of PUF ID traceability extended through CPB process/assembly stages for an advanced secure supply chain.