Robust true random number generator using hot-carrier injection balanced metastable sense amplifiers

Hardware true random number generators are an essential functional block in many secure systems. Current designs that use bi-stable elements balanced in the metastable region are capable of both high randomness and high bitrate. However, these designs require extensive support circuits to maintain balance in the metastable region, complex built-in self test loops to configure the support circuits, and suffer from sensitivity to environmental conditions. We propose a true random number generator design based around sense amplifier circuits that are balanced in the metastable region using hot carrier injection, rather than complex support circuits. Further, we show an architecture that maintains high entropy output across a range of ± 20% voltage variation. Experimental results from a prototype design in a 65nm bulk CMOS process demonstrate the efficacy of the proposed TRNG architecture, which passes all NIST tests.