In-NVRAM Unified PUF and TRNG Based on Standard CMOS Technology

Hardware security primitives provide Root-of-Trust (RoT) procedures for booting, authentication, and key generation processes in secure integrated systems. The RoT requires True Random Number Generators (TRNGs), Physical Unclonable Functions (PUFs), and non-volatile memories for essential key generation and identity authentication. However, these implementations introduce challenges due to the physical phenomena used in each primitive, requiring complex calibration or special technologies with additional masks. In addition, the integration of separated implementations in a single system-on-a-chip increases the area overhead. This work describes a unified PUF-TRNG in a Non-Volatile Random Access Memory (NVRAM) implementation in 180-nm CMOS technology. The PUF and TRNG primitives are based on the NVRAM metastability in the sense amplifier. The TRNG passes the statistical and entropy tests provided by NIST SP800-22 and SP800-90B, respectively. In addition, the normalized minimum entropy of the TRNG is 0.987 in the worst case with PVT (Process, Voltage, and Temperature) variations. The PUF uniformity, uniqueness and reliability are 49.85%, 48.12% and 99.58%, respectively at nominal conditions. Moreover, the PUF reach
$\mathbf{6735} F^{2}/\mathbf{bit}$
normalized area
^1
1
F
²
= (area)/(minimum feature size of the process)
²
. The NVRAM needs 8.5V for the programming and erasing modes. Finally, the unified implementation occupies
$\mathbf{43155}\mu m^{2}$
with
$\mathbf{1332}kF^{2}$
of normalized area.