Power management circuit with dual charge pump structure

1. An apparatus comprising:

a first switch network comprising a first capacitor;

a second switch network comprising a second capacitor; and

a connection switch coupled between the first switch network and the second switch network, wherein:

the first capacitor and the second capacitor are electrically coupled in series between a battery terminal and a ground terminal or electrically coupled in parallel between the battery terminal and the ground terminal during a charging phase;

the first capacitor and the second capacitor are electrically coupled in series between the battery terminal and a pump output terminal, or electrically coupled in parallel between the battery terminal and the pump output terminal, or electrically coupled in parallel between the ground terminal and the pump output terminal during a discharging phase;

the battery terminal is configured to provide a battery voltage, and the ground terminal is electrically coupled to ground; and

the pump output terminal is configured to provide a charge pump output voltage, which is eligible to be each of a half of, 1.5 times, 2 times, and 3 times the battery voltage.

2. The apparatus of claim 1 wherein:

the first capacitor and the second capacitor are electrically coupled in series between the battery terminal and the ground terminal during the charging phase; and

the first capacitor and the second capacitor are electrically coupled in parallel between the battery terminal and the pump output terminal during the discharging phase.

3. The apparatus of claim 1 wherein:

the first capacitor and the second capacitor are electrically coupled in series between the battery terminal and the ground terminal during the charging phase; and

the first capacitor and the second capacitor are electrically coupled in parallel between the ground terminal and the pump output terminal during the discharging phase.

4. The apparatus of claim 1 wherein:

the first capacitor and the second capacitor are electrically coupled in parallel between the battery terminal and the ground terminal during the charging phase; and

the first capacitor and the second capacitor are electrically coupled in series between the battery terminal and the pump output terminal during the discharging phase.

5. The apparatus of claim 1 wherein:

the first capacitor and the second capacitor are electrically coupled in parallel between the battery terminal and the ground terminal during the charging phase; and

the first capacitor and the second capacitor are electrically coupled in parallel between the battery terminal and the pump output terminal during the discharging phase.

6. The apparatus of claim 1 wherein the first capacitor has a same capacitance as the second capacitor.

7. The apparatus of claim 1 wherein the first switch network further comprises a first switch, a second switch, a third switch, and a fourth switch, wherein:

the first capacitor is coupled between a first flying node and a second flying node;

the first switch is coupled between the battery terminal and the first flying node, such that the battery terminal is connected to the first flying node when the first switch is closed;

the second switch is coupled between the first flying node and the pump output terminal, such that the first flying node is connected to the pump output terminal when the second switch is closed;

the third switch is coupled between the battery terminal and the second flying node, such that the battery terminal is connected to the second flying node when the third switch is closed; and

the fourth switch is coupled between the second flying node and the ground terminal, such that the second flying node is connected to the ground terminal when the fourth switch is closed.

8. The apparatus of claim 7 wherein the second switch network further comprises a fifth switch, a sixth switch, a seventh switch, and an eighth switch, wherein:

the second capacitor is coupled between a third flying node and a fourth flying node;

the fifth switch is coupled between the battery terminal and the third flying node, such that the battery terminal is connected to the third flying node when the fifth switch is closed;

the sixth switch is coupled between the third flying node and the pump output terminal, such that the third flying node is connected to the pump output terminal when the sixth switch is closed;

the seventh switch is coupled between the battery terminal and the fourth flying node, such that the battery terminal is connected to the fourth flying node when the seventh switch is closed; and

the eighth switch is coupled between the fourth flying node and the ground terminal, such that the fourth flying node is connected to the ground terminal when the eighth switch is closed.

9. The apparatus of claim 8 wherein the connection switch is coupled between the second flying node and the third flying node, such that the first capacitor and the second capacitor are coupled in series when the connection switch is closed.

10. The apparatus of claim 9 wherein the connection switch, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, and the eighth switch are field-effect transistors (FETs).

11. The apparatus of claim 9 wherein the connection switch, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, and the eighth switch are microelectromechanical system switches.

12. The apparatus of claim 9 further comprising a switch controller, which is configured to control the opening and closing of the connection switch, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, the sixth switch, the seventh switch, and the eighth switch.

13. The apparatus of claim 1 further comprising a power inductor coupled between the pump output terminal and a power supply terminal, wherein the power inductor is configured to filter power flowing between the pump output terminal and the power supply terminal.

14. The apparatus of claim 13 further comprising a battery switch and a ground switch, wherein:

the power inductor is coupled to the pump output terminal at an interior node;

the battery switch is coupled between the battery terminal and the interior node, such that the battery terminal is electrically coupled to the power inductor when the battery switch is closed; and

the ground switch is coupled between the interior node and ground, such that the ground terminal is electrically coupled to the power inductor when the ground switch is closed.

15. The apparatus of claim 14 further comprising a switch controller, which is configured to conduct current to the power inductor from one of the pump output terminal, the battery terminal, and the ground terminal.

16. The apparatus of claim 13 further including a tracking amplifier comprising:

a first input port coupled to the power supply terminal to receive a feedback signal;

a second input port configured to receive a target voltage; and

an output port coupled to the power supply terminal, wherein the tracking amplifier is configured to provide an amplified voltage in response to a difference between the target voltage and the feedback signal.

17. The apparatus of claim 16 further including an offset capacitor coupled between the output port of the tracking amplifier and the power supply terminal, wherein the offset capacitor is configured to provide an offset voltage to increase a dynamic range of the amplified voltage.

18. The apparatus of claim 16 further comprising a mode switch coupled between the output port of the tracking amplifier and the ground terminal, wherein the mode switch is configured to enable or disable the tracking amplifier.

19. The apparatus of claim 18 further comprising a switch controller, which is configured to control the opening and closing of the mode switch.