Unified Analog PUF and TRNG Based on Current-Steering DAC and VCO

This work presents a unified weak physical unclonable function (PUF) and a true random number generator (TRNG) based on the current-steering digital-to-analog converter (DAC) and ring voltage-controlled oscillator (VCO). Entropy source for the weak PUF is the mismatch between NMOS and PMOS transistors in a cascode current DAC as well as the mismatch between VCO quantizers, while entropy source for the TRNG is thermal noise in the DAC and VCO and clock jitter. Instead of using spatial entropy sources for the PUF, i.e., multiple unit PUF elements, the proposed architecture utilizes temporal entropy source by capturing the output of unit PUF element over multiple cycles, which reduces area significantly. A unified PUF/TRNG prototype is fabricated in 65-nm CMOS and consumes 0.36 pJ/bit at a throughput of 100 Mb/s. The PUF has a measured intra-HD of 0.0906 and inter-HD of 0.4859, while the raw TRNG bitstream has an entropy of 0.9991 and passes all the NIST statistical randomness tests.