A 144-fJ/Bit Reliable and Compact TRNG Based on the Diffusive Resistance of 3-D Resistive Random Access Memory

In this work, we harnessed the diffusiveness of the resistant states in 3-D resistive random access memory (RRAM) array and implemented a true random number generator (TRNG). The fluctuation of the resistance states serves as the random source, which is then amplified by peripheral ring oscillator (RO) circuits. The peripheral circuits are fabricated in a 55-nm CMOS process. Measurement results show that the TRNG supports a maximum throughput of 1 Gb/s and passes the NIST test across $-$ 40 $<^>{\circ}$ C to 125 $<^>{\circ}$ C. The RRAM cells enjoy good robustness under high temperature, as the baking experiment shows. The TRNG obviates the need for calibration circuits and requires no startup circuits. The proposed work harvests the fluctuation of analog resistance of RRAM cells, enriching the TRNG family aimed for Internet of Things (IoT) application.