Band-gap reference source circuit

The invention provides a band-gap reference source circuit. The band-gap reference source circuit has the advantages that the band-gap reference source circuit is provided with a first operational amplifier and a reference voltage output branch circuit on the basis of an existing band-gap reference source circuit, the reference voltage output branch circuit comprises a first PMOS (p-channel metal oxide semiconductor) transistor and a first bipolar transistor which are serially electrically connected with each other, one of two input ends of the first operational amplifier is connected to a control end of a bipolar transistor in a basic branch circuit, and the other input end of the first operational amplifier is connected to a control end of the first bipolar transistor of the reference voltage output branch circuit; a grid electrode of the first PMOS transistor is connected with an output end of the first operational amplifier, a source electrode of the first PMOS transistor is connected to a voltage VCC end, a drain electrode of the first PMOS transistor is a reference voltage output end, output reference voltages can be fed back to the first PMOS transistor by the first operational amplifier, feedback control can be carried out on output of the first PMOS transistor, accordingly, output of the reference voltages can be controlled, and the problem of influence of mismatching between devices on the accuracy of output voltages can be solved.