Patent ID: 8650233

Claim:
A random number generator comprising: a variable frequency oscillator that comprises: a selection circuit having multiple input terminals and an output terminal; a parallel circuit having an input terminal and multiple output terminals that are respectively connected to the input terminals of the selection circuit, the parallel circuit comprising one or more buffer circuits to be selected by the selection circuit; and an inverter circuit having a control terminal, the inverter circuit being connected to the input terminal of the parallel circuit and to the output terminal of the selection circuit; and a latch circuit connected to the variable frequency oscillator, wherein the variable frequency oscillator outputs a signal having a variable frequency, where T H is a time in which a level of the output signal is high and T L is a time in which the level of the output signal is low, the latch circuit has a setup time T SET and a hold time T HOLD , and min( T H ,T L )>( T SET +T HOLD ).