True Random Number Generation by Variability of Resistive Switching in Oxide-Based Devices

Scalable, low-power random number generator (RNG) blocks are essential for encryption in today´s communication systems. To allow for true RNG, a system must display an inherently-random physical phenomenon, such as the timing of individual fluctuations in random telegraph noise or the random trapping/detrapping phenomena in dielectrics. In this work, a true RNG based on set variability in a resistive switching memory (RRAM) is demonstrated. The RNG relies on a single RRAM device, which is repeatedly programmed at a constant voltage close to the nominal set voltage. Due to the statistical variability of the set voltage, set transition takes place only in 50% of the applied pulses, thus resulting in a bimodal distribution of resistance. The bimodal distribution of analog resistance is finally converted into a 0/1 distribution of output voltage values through digital regeneration with a CMOS inverter.