Reference voltage generator with bootstrapping effect
View Patent ↗An integrated electronic device for generating a reference voltage. The circuitry has a bias current generator for generating a first bias current, a diode element coupled to the bias current generator and fed by a second bias current derived from the first bias current for converting the second bias current into a reference voltage across the diode element, a supply voltage pre-regulator stage for regulating the supply voltage used for the bias current generator, and an output buffer coupled to the reference voltage for providing a low impedance output, wherein the reference voltage is coupled to the supply pre-regulator stage for biasing the supply pre-regulator stage by the reference voltage.
1. 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.
2. The apparatus of claim 1 , wherein the supply voltage pre-regulator further comprises:
a first current source that is coupled to the first supply rail;
a first PMOS transistor that is coupled to the first supply rail at its source, the first current source at its gate, and the output terminal of the supply voltage pre-regulator at its drain;
an NMOS transistor that is coupled to the first current source at its drain and the internal node of the supply voltage pre-regulator at its gate;
a second PMOS transistor that is coupled to the output terminal of the supply voltage pre-regulator at its source and the internal node of the supply voltage pre-regulator at its gate; and
a second current source that is coupled to the source of the NMOS transistor, the drain of the second PMOS transistor, and the second supply rail.
3. The apparatus of claim 2 , wherein the first current mirror further comprises:
a third PMOS transistor that is coupled to the output terminal of the supply voltage pre-regulator at its source and the control electrode of the output transistor at its gate; and
a fourth PMOS transistor that is coupled to the output terminal of the supply voltage-regulator at its source and the control electrode of the output transistor at its gate and drain.
4. The apparatus of claim 3 , wherein the NMOS transistor further comprises first NMOS transistor, and wherein the second current mirror further comprises:
a second NMOS transistor that is coupled to the second supply rail at its source and the drain of the third PMOS transistor at its gate and drain; and
a third NMOS transistor that is coupled to the control electrode of the output transistor at its drain, the gate of the second NMOS transistor at its gate, and the resistor at its source.
5. The apparatus of claim 4 , wherein the first passive electrode, the second passive electrode, and the control electrode of the output transistor further comprise a source, a drain, and a gate of a fifth PMOS transistor.
6. The apparatus of claim 5 , wherein the diode element further comprises:
a diode-connected NMOS transistor that is coupled to the drain of the fifth PMOS transistor; and
a diode-connected PNP transistor that is coupled between the diode-connected NMOS transistor and the second supply rail.
7. The apparatus of claim 5 , wherein the diode element further comprises:
a fourth NMOS transistor that is coupled to the is coupled to the drain of the fifth PMOS transistor at its drain; and
a diode-connected NMOS transistor that is coupled between the source of the fourth NMOS transistor and the second supply rail.
8. The apparatus of claim 7 , wherein the gate and source of the fourth NMOS transistor are coupled together.
9. The apparatus of claim 5 , wherein the diode element further comprises:
a sixth PMOS transistor that is coupled to the is coupled to the drain of the fifth PMOS transistor at its drain and the second supply rail at its gate; and
a diode-connected NMOS transistor that is coupled between the source of the sixth PMOS transistor and the second supply rail.