Patent ID: 8222884

Claim:
An apparatus comprising: a first supply rail; a second supply rail; a supply voltage pre-regulator that is coupled between the first supply rail and the second supply rail, wherein the supply voltage pre-regulator includes an output terminal and an internal node; a bias generator having: a first current mirror that is coupled to the output terminal of the supply voltage pre-regulator; a second current mirror that is coupled to the first current mirror and the second supply rail; a resistor that is coupled between at least a portion of the second current mirror and the second supply rail; and an output transistor having a first passive electrode, a second passive electrode, and a control electrode, wherein the first passive electrode of the output transistor is coupled to the output terminal of the supply voltage pre-regulator, and wherein the second passive electrode of the output transistor is coupled to the internal node of the supply voltage pre-regulator, and wherein the control electrode is coupled to a node between the first and second current mirrors; a diode element that is coupled to the second passive electrode of the output transistor; and an output buffer that is coupled to the second passive electrode of the output transistor and the first supply rail.