A reference voltage generator includes a voltage generation circuit, an amplifier, a diode unit and a transistor. The voltage generation circuit includes an output terminal for outputting a reference voltage, a first terminal having an operational voltage, and a second terminal. The amplifier includes an input terminal coupled to the first terminal of the voltage generation circuit, an output terminal, a first terminal coupled to a first voltage terminal, and a second terminal. The diode unit includes a first terminal coupled to the second terminal of the amplifier, and a second terminal coupled to the second terminal of the voltage generation circuit and a second voltage terminal. The transistor includes a first terminal coupled to the first terminal of the amplifier, a second terminal coupled to the output terminal of the voltage generation circuit, and a control terminal coupled to the output terminal of the amplifier.