0.6–1.2 V, 0.22 pJ/bit True Random Number Generator Based on SAR ADC

This brief proposes a true-random number generator (TRNG) based on a successive approximation register (SAR) analog-to-digital converter (ADC). After the SAR ADC has finished conversion, the comparator is fired again to quantize the residue. The 1-bit quantized residue acts as a true random sequence and no additional circuits are required for the TRNG. A prototype fabricated in 65nm process acts as a TRNG over 0.6V-1.2V power supply and -5°C to 50°C temperature range without any calibration or post-processing. The TRNG outputs a random sequence at 1.25Mbps and consumes state-of-the-art energy of 0.22pJ/bit.