3-Gb/s High-Speed True Random Number Generator Using Common-Mode Operating Comparator and Sampling Uncertainty of D Flip-Flop

True random number generators (TRNGs) are important in data encryption for information security applications. In this paper, we propose a TRNG that utilizes a comparator in the common-mode operation and the sampling uncertainty of a D flip-flop (DFF). The comparator output is affected by the input common-mode noise and the noise that is simultaneously self-induced. A slicer generates an unpredictable and asynchronous pulse to the input of the DFF according to the output-referred noise of the comparator. By sampling the random pulse with a 3-GHz external clock, there is a sampling uncertainty, which helps to increase the random quality. As a result, we use the independent two random sources for TRNG. The area of the designed circuit is 1609 μm². In spite of the small size, the data rate of the proposed TRNG is 3 Gb/s. We verify that the output bit stream passes all of the National Institute of Standards and Technology test suites. We fabricate the TRNG in a 65-nm CMOS process with a 1.2 V supply voltage. The power consumption of the proposed TRNG is 5 mW, and the energy per bit is 1.6 pJ/b.