A bistable cell includes a pair of inverters and multiple pairs of cross-coupled tristate buffers. Each pair of tristate buffers can be individually selected to implement an entropy harvesting state for the bistable cell. Each of the tristate buffers generally has lower strength than the inverters but the inverter-to-buffer strength ratio can be configured through selective use of one or more of the tristate buffer pairs. The resulting entropy harvesting state behavior can be varied based on the inverter-to-buffer strength ratio in terms of greater randomness of the output bits or decreased power consumption.

A bistable cell includes a pair of inverters and multiple pairs of cross-coupled tristate buffers. Each pair of tristate buffers can be individually selected to implement an entropy harvesting state for the bistable cell. Each of the tristate buffers generally has lower strength than the inverters but the inverter-to-buffer strength ratio can be configured through selective use of one or more of the tristate buffer pairs. The resulting entropy harvesting state behavior can be varied based on the inverter-to-buffer strength ratio in terms of greater randomness of the output bits or decreased power consumption.

A pulse counting circuit receives pulses supplied by a source circuit having at least two inverted pulse signal supply terminals. The circuit includes a first counter to count pulses of a first pulse signal and supply a first count and a second counter to count pulses of a second pulse signal and supply a second count. A selection circuit selects one of the first and second counts.

A pulse counting circuit receives pulses supplied by a source circuit having at least two inverted pulse signal supply terminals. The circuit includes a first counter to count pulses of a first pulse signal and supply a first count and a second counter to count pulses of a second pulse signal and supply a second count. A selection circuit selects one of the first and second counts.

A circuit generates a number of oscillations. The circuit includes a first branch with at least one delay line introducing symmetrical delays on rising edges and on falling edges and at least one asymmetrical delay element introducing different delays on rising edges and on falling edges. The circuit further includes a second branch looped back on the first branch and including at least one delay line introducing symmetrical delays on rising edges and on falling edges.

A logic two-to-one multiplexer includes: two input terminals; one output terminal; a control terminal. Four series-connected two-to-one multiplexers are connected such that a first multiplexer has its inputs connected to the input terminals, a last multiplexer has its output connected to the output terminal, and the other multiplexers have their respective inputs interconnected to the output of the previous multiplexer in the series association. Half of the multiplexers are controlled in reverse with respect to the other half of the multiplexers.

According to one embodiment, a random number generator includes a first circuit which outputs a second oscillation signal having a predetermined duty ratio on the basis of a first oscillation signal, a second circuit which latches values on the basis of the second oscillation signal and a clock having a frequency lower than a frequency of the second oscillation signal, a third circuit which outputs a control signal on the basis of the values, and a fourth circuit which controls the first circuit on the basis of the control signal.

A spread spectrum clock generator circuit includes a phase comparator; an oscillator to output an output clock signal; a phase selector to select one of phases equally dividing one cycle of the output clock signal, and to generate a phase shift clock signal having a rising edge in the selected phase; and a phase shift controller to control the phase selector. The phase shift controller generates a variable phase shift amount; determines the phase of the rising edge so that the cycle of the phase shift clock signal has a length changed from the cycle of the output clock signal by the variable phase shift amount added with a fixed phase shift amount; and changes a setting of an SS modulation profile if the selected phase exceeds an upper limit, falls below a lower limit, or is within the upper and lower limits.

A sampler adapted to a one-dimension slow-varying signal, including: a signal preprocessing unit configured to preprocess an input signal; a slope-controllable sawtooth wave signal generating unit configured to generate a slope-controllable sawtooth wave signal and perform zero-resetting; a signal comparing unit configured to compare the preprocessed input signal from the signal preprocessing unit with the sawtooth wave signal and to output a pulse signal to the generating unit and a signal outputting unit when the preprocessed input signal is equal to the sawtooth wave signal; a counting unit configured to count a number of clock signals while the sawtooth wave signal generating unit is generating the sawtooth wave signal and to transmit the counted number to the signal outputting unit; the signal outputting unit configured to, upon receipt of the pulse signal output from the signal comparing unit, output the number counted by the counting unit at the moment.

A sampler adapted to a one-dimension slow-varying signal, including: a signal preprocessing unit configured to preprocess an input signal; a slope-controllable sawtooth wave signal generating unit configured to generate a slope-controllable sawtooth wave signal and perform zero-resetting; a signal comparing unit configured to compare the preprocessed input signal from the signal preprocessing unit with the sawtooth wave signal and to output a pulse signal to the generating unit and a signal outputting unit when the preprocessed input signal is equal to the sawtooth wave signal; a counting unit configured to count a number of clock signals while the sawtooth wave signal generating unit is generating the sawtooth wave signal and to transmit the counted number to the signal outputting unit; the signal outputting unit configured to, upon receipt of the pulse signal output from the signal comparing unit, output the number counted by the counting unit at the moment.