Band-gap reference voltage circuit

A band-gap reference voltage circuit including a constant current generator and a reference voltage generator. The reference voltage generator includes a first transistor, a second resistor, a first transistor and a second transistor, and the emitter area of the first transistor is larger than the emitter area of the second transistor. The base, collector of the first transistor and a terminal of the first resistor are electrically connected to the current generator; and the emitter of the first transistor is electrically connected to the collector of the second transistor; and the base of the second transistor is electrically connected to the other terminal of the first resistor. The collector voltage is used as the reference voltage; the second resistor is disposed between the base and the emitter of the second transistor. The current supplied by the constant current generator enables the transistor to operate in the active region.