Distributed random-number generator

A Random-Number Generator (RNG) includes a first plurality of High-Frequency (HF) clock generators, a second plurality of Low-Frequency (LF) clock generators, a third plurality of Digital Random-Number Generator circuits (DRNGs), and a multiplexer. The HF clock generators are configured to generate respective HF clock signals in a first frequency range. The LF clock generators are configured to generate respective LF clock signals in a second frequency range, lower than the first frequency range. Each DRNG is configured to derive a respective random-bit sequence from (i) a respective HF clock signal taken from among the HF clock signals and (ii) a respective LF clock signal taken from among the HF clock signals. The multiplexer is configured to produce an output sequence of random bits from random-bit sequences generated by the DRNGs.