A process and temperature tolerant oscillator-based true random number generator with dynamic 0/1 bias correction

This paper presents an oscillator-based true random number generator (TRNG) that dynamically unbiases 0/1 probability. The proposed TRNG automatically adjusts the duty cycle of a fast oscillator to 50 %, and generates unbiased random numbers tolerating process variation and dynamic temperature fluctuation. A prototype chip of the proposed TRNG was fabricated with a 65 nm CMOS process. Measurement results show that the developed duty cycle monitor obtained the probability of `1´ 4,100 times faster than the conventional output bit observation, or estimated the probability with 70 times higher accuracy. The proposed TRNG adjusted the probability of `1´ to within 50±0.07 % in five chips in the temperature range of 0 °C to 75 °C. Consequently, the proposed TRNG passed the NIST and DIEHARD tests at 7.5 Mbps with 6,670 μm² area.