CMOS-MEMS PUF Exploiting Mode Localization in a Multi-DOF Tuned-Mass-Damper Resonator

This work demonstrates, for the first time, a physical unclonable function (PUF) based on a CMOS-MEMS multi-degree-of-freedom (DoF) tuned-mass-damper (TMD) resonator. In particular, building upon the TMD's mode-splitting mechanism and its acute sensitivity to process variations, this study leverages multiple TMD beams to introduce additional modal DoFs, which significantly enhance the mode-localized distributions. This technique amplifies random manufacturing variations, resulting in an enriched and unique transient free-decay signature in the resonator's time-domain response following a pulse excitation. From 22 fabricated devices, the inter-device Hamming distance (inter-HD) exhibits an ideal mean of$\mu=0.4980$with a standard deviation of$\sigma=0.0364$, and the generated bitstreams successfully pass all NIST randomness tests, confirming strong uniqueness and randomness. While repeated measurements show a non-ideal intra-device Hamming distance (intra-HD) of$\mu=0.2968$and$\sigma=0.0324$, indicating native bit instability common to many PUF designs, this can be effectively addressed using standard error-correction schemes.