A voltage bandgap circuit comprises a first transistor and a second transistor connected in a voltage bandgap circuit arrangement, the area of the first transistor is selected to be a predetermined multiple of the area of the second transistor; a differential input amplifier has a first input coupled to the first transistor and a second input coupled to the second transistor; the amplifier has its output coupled to an output node. A first trimmable resistance network is coupled to say the bandgap circuit and is trimmed to adjust the output voltage of the bandgap circuit based upon a single temperature voltage measurement made across two of the terminals of each transistor.