A Low Area Random Number Generator Based on Stability Changes of Ring Oscillators

This paper presents a new random number generator based on stability changes of ring oscillators. Multiplexer and inverter are added to each ring to be able to turn on and off the oscillations. Fourteen ring oscillators are combined with the XOR gate after each ring’s output is sampled with a D type flip-flop. The multiplexers are controlled with a control unit. The designed TRNG is subjected to NIST SP800-22 test suite that contains statistical tests for randomness. 320 million consecutive bits are collected as 320 bitstreams with a data acquisition card. The collected data passed all the randomness requirements of the NIST SP800-22 test suite. Comparisons with wake-up and shut-down methods are performed to show the improvement provided by the proposed new method. Up to 44% improvement in the area, up to 41% improvement in resource usage, and 100% improvement in throughput are obtained. All TRNG designs are implemented in Xilinx Virtex V xc5vlx50t FPGA.