0.36-mW, 52-Mbps True Random Number Generator Based on a Stochastic Delta–Sigma Modulator

This letter presents a true random number generator (TRNG) based on a stochastic delta-sigma modulator (DSM) with ring oscillator (RO) integrators. The TRNG leverages noise and jitter in the ROs as entropy source. A multibit nonreturn-to-zero (NRZ) digital-to-analog converter (DAC) in the feedback path ensures DSM noise dominates input swing seen by the front-end integrators. Hence, the DSM can concurrently operate as an ADC and TRNG. A 65-nm prototype achieves Shannon entropy > 0.999998 with lower-bound min-entropy > 0.995 at 52 Mb/s throughput while passing all NIST tests across multiple chips and voltage/temperature corners without needing calibration. The combined power consumption of ADC and TRNG is 0.36 mW which is the lowest among state-of-the-art RO TRNGs. Low power consumption, high entropy, and concurrent operation of the TRNG as an ADC are principal contributions of this letter.