Robust random chip ID generation with wide-aperture clocked comparators and maximum likelihood detection

In many applications, mass-produced chips need to be tagged with individual identification numbers (i.e. chip ID). One way to do this without requiring post-fabrication programming steps is to generate the unique ID per chip exploiting random device mismatch. However, it can be prone to mis-identification due to time-varying noise that may cause a different ID to be read from the same chip each time. This paper presents a wide-aperture, low-noise clocked comparator design and a novel ID detection scheme based on maximum likelihoods (ML) that can significantly reduce the probability of mis-identification for such random chip ID generators. A prototype chip fabricated in 0.18-μm CMOS demonstrates the measured input-referred noise of the comparator as low as 265-μV_rms, while preserving the wide input-referred offset distribution of 22-mV_rms. As for the detection scheme, the analysis shows that when detecting 1024 unique IDs, the proposed ML detection scheme can achieve the mis-identification rate of 1.73×10^-18 with 64-bits while the previous scheme based on Hamming distances (HD) would require 90-bits.