RANDOM NUMBER GENERATING CIRCUIT

Provided is a random number generating circuit having a simple circuit structure, for generating a physical random number based on a noise. The random number generating circuit includes a reference voltage section, an inverting amplifier section having a threshold voltage equal to a reference voltage level, and a semiconductor switch provided between an output terminal of the reference voltage section and an input terminal of the inverting amplifier section. A thermal noise produced from the reference voltage section is held by the semiconductor switch and a capacitor and amplified by the inverting amplifier section to generate the physical random number.