Low cost and energy, thermal noise driven, probability modulated random number generator

Random Number Generators (RNGs) constitute the essential foundation of many applications, e.g., cryptographic technology, and statistic based computing. The vast majority of RNG proposals, generate binary sequences with uncorrelated and equiprobable bits. However, in certain applications, such as stochastic computing, the binary sequence is required to be generated not with 0.5 logic “1” probability, but with a custom specified one. This paper presents a probability modulated True Random Number Generator (TRNG), that produces binary sequences with a desired probability of logic “1”, according to a value resident in a register. The proposed circuit relies on the thermal noise as random signal source and it was implemented in 65nm CMOS technology. Simulation results reveal a quasi-linear dependence, between the output logic “1” probability sampled at 1GHz, and the modulating voltage (obtained from the register value by mean of a D/A converter) over a range of 20mV. For a desired probability of 0.5, the sequences randomness was validated by the NIST tests.