A 82nW chaotic-map true random number generator based on sub-ranging SAR ADC

An ultra-low power true random number generator (TRNG) based on sub-ranging SAR ADC is proposed. The proposed TRNG shares the coarse-ADC circuit with sub-ranging SAR ADC for area reduction. The shared coarse-ADC not only plays the role of discrete-time chaotic circuit or TRNG's entropy source but also reduces overall SAR ADC energy consumption by selectively activating the fine-SAR ADC. Also, the proposed dynamic residue amplifier and adaptive-reset comparator generate chaotic map with low power consumption. TRNG core occupies 0.0045mm2 in 0.18μm CMOS technology and consumes 82nW at 270kbps throughput with 0.6V supply. The proposed TRNG passes all NIST tests and it achieves a state-of-the-art FOM of 0.3pJ/bit.