Fast-switching power management circuit operable to prolong battery life

1. A fast-switching power management circuit comprising:

a voltage circuit configured to generate a reference voltage at a reference node and an output voltage at a voltage output based on a battery voltage;

a first hybrid circuit and a second hybrid circuit each coupled between the reference node and the voltage output and configured to adjust the output voltage in each of a plurality of time intervals based on the reference voltage, the plurality of time intervals each corresponding to an orthogonal frequency division multiplexing (OFDM) symbol and comprising a switching window from a start of a respective one of the plurality of time intervals; and

a control circuit configured to:

receive a target voltage during a present time interval among the plurality of time intervals indicating that the output voltage will change from a present voltage level in the present time interval to a future voltage level in a future time interval immediately succeeding the present time interval among the plurality of time intervals; and

activate a first one of the first hybrid circuit and the second hybrid circuit during the present time interval to thereby cause the output voltage to change from the present voltage level to the future voltage level within the switching window of the future time interval.

2. The fast-switching power management circuit of claim 1 , wherein the control circuit is further configured to activate the first one of the first hybrid circuit and the second hybrid circuit independent of whether a second one of the first hybrid circuit and the second hybrid circuit is activated.

3. The fast-switching power management circuit of claim 1 , further comprising:

a first coupling switch provided between the first hybrid circuit and the voltage output;

a second coupling switch provided between the second hybrid circuit and the voltage output;

a first offset capacitor provided between a first coupling node located between the first hybrid circuit and the first coupling switch and a ground; and

a second offset capacitor provided between a second coupling node located between the second hybrid circuit and the second coupling switch and the ground.

4. The fast-switching power management circuit of claim 3 , wherein the control circuit is further configured to:

receive the target voltage indicating that the output voltage will increase from the present voltage level in the present time interval to the future voltage level in the future time interval;

open a respective one of the first coupling switch and the second coupling switch that is coupled to the first one of the first hybrid circuit and the second hybrid circuit; and

activate the first one of the first hybrid circuit and the second hybrid circuit to charge a respective one of the first offset capacitor and the second offset capacitor to the future voltage level within the switching window from the start of the future time interval.

5. The fast-switching power management circuit of claim 4 , wherein the control circuit is further configured to close the respective one of the first coupling switch and the second coupling switch at the start of the future time interval to thereby cause the output voltage to be maintained at the future voltage level during the future time interval.

6. The fast-switching power management circuit of claim 5 , wherein the control circuit is further configured to deactivate the first one of the first hybrid circuit and the second hybrid circuit no later than an end of the switching window in the future time interval.

7. The fast-switching power management circuit of claim 4 , wherein the control circuit is further configured to:

deactivate a second one of the first hybrid circuit and the second hybrid circuit prior to the start of the future time interval; and

open a respective one of the first coupling switch and the second coupling switch that is coupled to the second one of the first hybrid circuit and the second hybrid circuit at the start of the future time interval.

8. The fast-switching power management circuit of claim 3 , further comprising:

a first pulldown switch coupled between the first coupling node and the ground; and

a second pulldown switch coupled between the second coupling node and the ground.

9. The fast-switching power management circuit of claim 8 , wherein the control circuit is further configured to:

receive the target voltage indicating that the output voltage will decrease from the present voltage level in the present time interval to the future voltage level in the future time interval;

open the respective one of the first coupling switch and the second coupling switch that is coupled to the first one of the first hybrid circuit and the second hybrid circuit; and

cause a respective one of the first offset capacitor and the second offset capacitor to discharge to the future voltage level within the switching window from the start of the future time interval.

10. The fast-switching power management circuit of claim 9 , wherein the control circuit is further configured to:

deactivate a second one of the first hybrid circuit and the second hybrid circuit prior to the start of the future time interval; and

open a respective one of the first coupling switch and the second coupling switch that is coupled to the second one of the first hybrid circuit and the second hybrid circuit at the start of the future time interval.

11. The fast-switching power management circuit of claim 9 , wherein the control circuit is further configured to:

determine that the future voltage level is higher than the battery voltage; and

activate the first one of the first hybrid circuit and the second hybrid circuit to harvest electrical potential energy from the respective one of the first offset capacitor and the second offset capacitor.

12. The fast-switching power management circuit of claim 9 , wherein the control circuit is further configured to:

determine that the present voltage level is higher than the battery voltage and the future voltage level is lower than the battery voltage; and

activate the first one of the first hybrid circuit and the second hybrid circuit to harvest electrical potential energy from the respective one of the first offset capacitor and the second offset capacitor.

13. The fast-switching power management circuit of claim 12 , wherein the control circuit is further configured to:

determine that the present voltage level is reduced to the battery voltage;

deactivate the first one of the first hybrid circuit and the second hybrid circuit; and

close the respective one of the first pulldown switch and the second pulldown switch to continue discharging the respective one of the first offset capacitor and the second offset capacitor to the future voltage level.

14. The fast-switching power management circuit of claim 9 , wherein the control circuit is further configured to:

determine that the present voltage level is lower than or equal to the battery voltage;

deactivate the first one of the first hybrid circuit and the second hybrid circuit; and

close a respective one of the first pulldown switch and the second pulldown switch that is coupled to the first coupling node to thereby discharge the respective one of the first offset capacitor and the second offset capacitor to the future voltage level.

15. The fast-switching power management circuit of claim 1 wherein the voltage circuit comprises:

a multi-level charge pump configured to generate a low-frequency voltage at multiple levels based on the battery voltage and in accordance with a selected duty cycle; and

an inductor-capacitor (LC) filter circuit coupled between the multi-level charge pump and the voltage output and configured to average the multiple levels of the low-frequency voltage to generate the output voltage at the voltage output.

16. The fast-switching power management circuit of claim 15 wherein the multi-level charge pump comprises:

an input node coupled to a voltage source to receive the battery voltage;

an output node coupled to the LC filter circuit to output the low-frequency voltage;

a first switch coupled between the input node and the reference node;

a second switch coupled between the reference node and the output node;

a third switch coupled between the input node and an intermediate node;

a fourth switch coupled between the intermediate node and a ground;

a fifth switch coupled between the input node and the output node;

a sixth switch coupled between the output node and the ground; and

a fly capacitor coupled between the reference node and the intermediate node.

17. The fast-switching power management circuit of claim 16 wherein the control circuit is further configured to:

close the first switch, close the fourth switch, and open the third switch concurrently to charge the fly capacitor to the battery voltage; and

open the first switch, open the fourth switch, and close the third switch concurrently to generate the reference voltage higher than the battery voltage at the reference node.

18. The fast-switching power management circuit of claim 17 wherein the control circuit is further configured to close the fifth switch to cause the multi-level charge pump to output the low-frequency voltage at the battery voltage to thereby cause the LC filter circuit to generate the output voltage at the battery voltage.

19. The fast-switching power management circuit of claim 1 , wherein the first hybrid circuit and the second hybrid circuit are each configured to:

operate as a closed switch when being activated; and

operate as an open switch when being deactivated.