One example discloses a voltage reference, including: a bandgap circuit core having a first intermediate bandgap voltage output, a second intermediate bandgap voltage output, and a bandgap voltage reference output; an amplifier having a first input, a second input, an input offset, an output, and an input_offset_trim; a trim controller; a switch matrix coupled between the bandgap circuit, the amplifier and the trim controller; wherein the switch matrix has a functional configuration and a calibration configuration; wherein in the functional configuration of the switch matrix, the first intermediate bandgap voltage output is coupled to the first input of the amplifier and the second intermediate bandgap voltage output is coupled to the second input of the amplifier; and wherein in response to the calibration configuration of the switch matrix, the trim controller is coupled to adjust the input offset of the amplifier using the input_offset_trim.