A bandgap reference circuit comprising a current mirror, an operational amplifier, first and second BJT transistors is disclosed. The current mirror comprises a first input terminal, a second input terminal and at least one output terminal. The operational amplifier is coupled to the current mirror, wherein a first transistor and a second transistor respectively coupled to the first and the second input terminals have a zero or near zero threshold voltage. The first and second BJT transistors are coupled to two input terminals of the operational amplifier respectively, wherein at least one of the first and second BJT transistors is coupled to the output terminal of the current mirror through a conductive path.