Compact floating-gate true random number generator

Introduction: Random number generation is indispensable in cryptography, scientific computing and stochastic computing. In cryptography, the quality of randomness of the generator is critical for security [1]. The pseudo-RNG generates sequences using a deterministic algorithm, so the sequence inevitably repeats and becomes predictable. A true RNG is nondeterministic and unpredictable, often relying on the randomness of physical noise. IC-compatible, true-RNG circuits are increasingly required in system-on-chip solutions for secure communication and stochastic computation. Noise amplification with thresholding, oscillator sampling, discrete-time chaos and metastability have all been used previously in IC-based RNGs [2, 3]. In this Letter, we present a new, true-RNG IC using the competition between noise sources. The circuit is very compact with less than 20 transistors. We use hot-electron injection in floating-gate MOSFETs in a negative feedback configuration to cancel fabrication mismatch and set the probability close to 50%. In the results to follow, we demonstrate high-quality randomness and robustness against interference by observing bit sequences generated by fabricated chips.