Patent ID: 7583070

Claim:
A band-gap voltage reference circuit, comprising: a current mirror coupled to an upper power rail; a first current path having a first bipolar junction transistor with a collector coupled to the current mirror through a first resistor, and an emitter coupled to a lower power rail, wherein the collector is coupled to a base of the first bipolar transistor; a second current path having second bipolar junction transistor and a second resistor, wherein a collector of the second bipolar junction transistor is coupled to the current mirror, a base of the second bipolar junction transistor coupled to the base of the first bipolar transistor, and where the second resistor is coupled between an emitter of the second bipolar junction transistor and the lower power rail; and a start-up circuit having an output, wherein the output is coupled to the first current path, the start-up circuit comprising, a start-up circuit current mirror, a start-up voltage reference coupled to a first output of the start-up circuit current mirror, and an output transistor coupled between a second output of the start-up circuit current mirror and the output of the start-up circuit, wherein an input of the output transistor is coupled to the first output of the current mirror and the start-up voltage reference and where the output transistor is controlled by the voltage difference between a voltage of the start-up voltage reference and a voltage of the first current path, wherein the start-up circuit is adapted to turn off when the voltage of the output of the start-up circuit coupled to the first current path is greater than the start-up voltage reference.