A bandgap reference circuit. In the bandgap reference circuit, a current generator includes a first bipolar junction transistor (BJT) and generates a first positive temperature coefficient current thereby producing a negative temperature coefficient voltage between a base terminal and an emitter terminal of the first bipolar junction transistor. A single-end gain amplifier includes a positive input terminal coupled to the emitter terminal of first the bipolar junction transistor. A first resistor is coupled between the output terminal of the single-end gain amplifier and an output terminal of the bandgap reference circuit to generate a first current. A current-to-voltage converter is coupled to the first resistor to convert the first positive temperature coefficient current and the first current to a bandgap voltage.