Abstract: A random number generator comprising a sigma-delta modulator, the sigma-delta modulator having a modulation unit and a feedback loop arranged to receive a digital output signal from the modulator and form an adjustment signal in dependence on the digital output signal such that at any given time the absolute difference between an amplitude of a summation output signal of the modulator and a quantizer threshold of the modulator is less than the first voltage range. The random number generator is thus capable of forming a digital output signal that has a high degree of entropy.

Abstract: A random number generator comprising a sigma-delta modulator, the sigma-delta modulator having a modulation unit and a feedback loop arranged to receive a digital output signal from the modulator and form an adjustment signal in dependence on the digital output signal such that at any given time the absolute difference between an amplitude of a summation output signal of the modulator and a quantizer threshold of the modulator is less than the first voltage range. The random number generator is thus capable of forming a digital output signal that has a high degree of entropy.

Abstract: A switch circuit comprising a mechanical switch having two contact elements, the switch being operable to bring the two contact elements into physical contact and thereby output an analog switch signal representative of operation of the switch and a sigma-delta modulator arranged to receive the analog switch signal and to output a digital switch signal in dependence thereon, the sigma-delta modulator having a frequency response such that it can suppress a relatively high frequency component of the analog input signal and thereby effectively debounce the output of the switch.