Multiple output charge pump with multiple flying capacitors

1. A multiple output charge pump comprising:

a first flying capacitor;

a second flying capacitor;

a first output node to provide a first voltage;

a second output node, distinct from the first output node, to provide a second voltage different than the first voltage; and

a switching network configured to provide a first mode of operation in which the first and second flying capacitors are connected in one of in series with one another between an input voltage and ground or in parallel with one another between the input voltage and ground, a second mode of operation in which the first and second flying capacitors are connected in parallel with one another between ground and the second output node, and a third mode of operation.

2. The multiple output charge pump of claim 1 further comprising:

a first output capacitor coupled between the first output node and ground; and

a second output capacitor coupled between the second output node and ground.

3. The multiple output charge pump of claim 2 wherein for the first mode of operation the first and second flying capacitors are connected in series between the input voltage and ground.

4. The multiple output charge pump of claim 3 wherein for the third mode of operation the first and second flying capacitors are connected in parallel with one another between the input voltage and the first output node.

5. The multiple output charge pump of claim 4 wherein for the second mode of operation the second output capacitor is charged to a voltage of −0.5 times the input voltage, and for the third mode of operation the first output capacitor is charged to a voltage of 1.5 times the input voltage.

6. The multiple output charge pump of claim 5 wherein the first and second flying capacitors each includes a positive electrode and a negative electrode and the switching network includes:

a first MOSFET connected between the positive electrode of the first flying capacitor and the input voltage;

a second MOSFET connected between the negative electrode of the second flying capacitor and ground;

a third MOSFET connected between the positive electrode of the first flying capacitor and the first output node;

a fourth MOSFET connected between the negative electrode of the second flying capacitor and the second output node; and

a fifth MOSFET connected between the negative electrode of the first flying capacitor and the positive electrode of the second flying capacitor.

7. The multiple output charge pump of claim 4 wherein for the second mode of operation the second output capacitor is charged to a voltage of 0.5 times the input voltage, and for the third mode of operation the first output capacitor is charged to a voltage of 1.5 times the input voltage.

8. The multiple output charge pump of claim 7 wherein the first and second flying capacitors each includes a positive electrode and a negative electrode and the switching network includes:

a first MOSFET connected between the positive electrode of the first flying capacitor and the input voltage;

a second MOSFET connected between the negative electrode of the second flying capacitor and ground;

a third MOSFET connected between the positive electrode of the first flying capacitor and the first output node;

a fourth MOSFET connected between the positive electrode of the second flying capacitor and the second output node; and

a fifth MOSFET connected between the negative electrode of the first flying capacitor and the positive electrode of the second flying capacitor.

9. The multiple output charge pump of claim 8 wherein the switching network further includes:

a sixth MOSFET connected between the positive electrode of the first flying capacitor and the second output node; and

a seventh MOSFET connected between the positive electrode of the second flying capacitor and the first output node.

10. The multiple output charge pump of claim 9 wherein the third and seventh MOSFETs each includes a drain-to-source P-N diode having a cathode connected to the first output node, and the fourth and sixth MOSFETs each includes a respective body bias generator to eliminate any source-to-drain parasitic diode conduction between a source and a drain of the fourth MOSFET and the sixth MOSFET, respectively.

11. The multiple output charge pump of claim 3 wherein for the third mode of operation the first and second flying capacitors are connected in series with one another between ground and the first output node.

12. The multiple output charge pump of claim 11 wherein for the second mode of operation the second output capacitor is charged to a voltage of −0.5 times the input voltage, and for the third mode of operation the first output capacitor is charged to a voltage of −1 times the input voltage.

13. The multiple output charge pump of claim 12 wherein the first and second flying capacitors each includes a positive electrode and a negative electrode and the switching network includes:

a first MOSFET connected between the positive electrode of the first flying capacitor and the input voltage;

a second MOSFET connected between the negative electrode of the second flying capacitor and ground;

a third MOSFET connected between the negative electrode of the first flying capacitor and the first output node;

a fourth MOSFET connected between the negative electrode of the second flying capacitor and the second output node; and

a fifth MOSFET connected between the negative electrode of the first flying capacitor and the positive electrode of the second flying capacitor.

14. The multiple output charge pump of claim 13 wherein the switching network further includes:

a sixth MOSFET connected between the negative electrode of the second flying capacitor and the first output node.

15. The multiple output charge pump of claim 14 where the fourth MOSFET includes a drain-to-source P-N diode having a cathode connected to the negative terminal of the second flying electrode and an anode connected to the second output node, and the third and sixth MOSFETs each includes a respective body bias generator to eliminate any source-to-drain parasitic diode conduction between a source and a drain of the third MOSFET and the sixth MOSFET, respectively.

16. The multiple output charge pump of claim 2 wherein for the first mode of operation the first and second flying capacitors are connected in parallel with one another between the input voltage and ground.

17. The multiple output charge pump of claim 16 wherein for the third mode of operation the first and second flying capacitors are connected in series with one another between ground and the first output node.

18. The multiple output charge pump of claim 17 wherein for the second mode of operation the second output capacitor is charged to a voltage of −1 times the input voltage, and for the third mode of operation the first output capacitor is charged to a voltage of −2 times the input voltage.

19. The multiple output charge pump of claim 18 wherein the first and second flying capacitors each includes a positive electrode and a negative electrode and the switching network includes:

a first MOSFET connected between the negative electrode of the first flying capacitor and the input voltage;

a second MOSFET connected between the negative electrode of the second flying capacitor and ground;

a third MOSFET connected between the negative electrode of the first flying capacitor and the first output node;

a fourth MOSFET connected between the negative electrode of the second flying capacitor and the second output node; and

a fifth MOSFET connected between the negative electrode of the first flying capacitor and the positive electrode of the second flying capacitor.

20. The multiple output charge pump of claim 19 wherein the switching network further includes a sixth MOSFET connected between the negative electrode of the second flying capacitor and the first output node.

21. The multiple output charge pump of claim 20 wherein the fourth MOSFET includes a drain-to-source P-N diode having a cathode connected to the negative electrode of the second flying capacitor and an anode connected to the second output node, and the third and sixth MOSFETs each includes a respective body bias generator to eliminate any source-to-drain parasitic diode conduction between a source and a drain of the third MOSFET and the sixth MOSFET, respectively.

22. A method of operating a multiple output charge pump that includes a first flying capacitor, a second flying capacitor, a first output, a second output, and a switching network, the method comprising:

configuring the switching network to operate the charge pump in a first mode in which the first and second flying capacitors are connected in one of in series with one another between and input voltage and ground or in parallel with one another between the input voltage and ground:

configuring the switching network to operate the charge pump in a second mode in which the first and second flying capacitors are connected in parallel with one another between ground and one of the first output and the second output; and

configuring the switching network to operate the charge pump in a third mode in which the first and second flying capacitors are connected in one of in parallel with one another between the input voltage and the other of the first output and the second output or in series with one another between ground and the other of the first output and the second output.