Power conversion by a phase-controlled cascade of an inductor-based power supply and a charge pump

1. A circuit for delivering power to a load, the circuit comprising:

a first terminal for receiving an input voltage or current;

a switched-capacitor charge pump circuit operated by one or more first clock signals, and comprising at least two storage capacitors;

an inductor-based power supply circuit, wherein the switched-capacitor charge pump circuit is coupled in cascade with the inductor-based power supply circuit between the first terminal and a second terminal according to one or more second clock signals; and

a control circuit that generates the one or more first clock signals and the one or more second clock signals so that the one or more second clock signals have a phase offset with respect to the one or more first clock signals that is set to adjust a conversion ratio of the cascaded combination of the switched-capacitor charge pump circuit and the inductor-based power supply circuit.

2. The circuit of claim 1 , wherein the switched-capacitor charge pump circuit comprises at least two switches, respectively controlled by separate phases of the second clock signal, to apply or receive inductor current in alternation to or from the at least two storage capacitors of the switched-capacitor charge pump circuit.

3. The circuit of claim 2 , wherein the switched-capacitor charge pump circuit comprises:

a first charge pump circuit comprising a first capacitor of the at least two storage capacitors and a first plurality of switches separate from the at least two switches and operated by first phases of the one or more first clock signals; and

a second charge pump circuit coupled in parallel with the first charge pump circuit and comprising a second capacitor of the at least two storage capacitors, wherein the second charge pump circuit further comprises a second plurality of switches separate from the at least two switches and operated by second phases of the one or more first clock signals that are complementary with the first phases of the one or more first clock signals, so that the second charge pump circuit operates in an opposite phase from the first charge pump circuit with respect to the one or more first clock signals.

4. The circuit of claim 3 , wherein the first charge pump circuit further comprises at least one third capacitor coupled to the first capacitor by at least one switch of the first plurality of switches, and wherein the second charge pump circuit further comprises at least one fourth capacitor coupled to the second capacitor by at least one switch of the first plurality of switches.

5. The circuit of claim 2 , wherein a duty cycle of the one or more first clock signals and a duty cycle of the one or more second clock signals are in a range between 40 and 60 percent.

6. The circuit of claim 2 , wherein the first terminal is an input terminal that supplies a connection to a DC input voltage source through an external inductance, wherein the at least two switches of the switched-capacitor charge pump circuit direct current from the external inductance to provide input current to the switched-capacitor charge pump circuit, and wherein the switched-capacitor charge pump circuit has an output coupled to the second terminal to deliver the power to the load.

7. The circuit of claim 1 , wherein the circuit is a power supply for providing power supply voltages to another electronic circuit.

8. The circuit of claim 1 , wherein the first terminal is coupled to an input of the charge pump, and wherein an output of the charge pump is coupled to an input of the inductor-based power supply circuit, and wherein the output of the inductor-based power supply circuit has an output coupled to the second terminal to deliver the power to the load.

9. The circuit of claim 8 , wherein in a first operating mode, the cascaded combination of the switched-capacitor charge pump circuit and the inductor-based power supply circuit transfers energy from the first terminal to the second terminal, and wherein in a second operating mode, the cascaded combination of the switched-capacitor charge pump circuit and the inductor-based power supply circuit transfers energy from the second terminal to the first terminal.

10. The circuit of claim 9 , wherein the first terminal is coupled to a battery that is discharged through the circuit to the second terminal in the first operating mode, and wherein the circuit charges the battery from an energy source coupled to the second terminal in the second operating mode.

11. A circuit for delivering power to an inductive load, the circuit comprising:

a first terminal for receiving an input voltage or current;

a switched-capacitor charge pump circuit operated by one or more first clock signals, comprising at least two storage capacitors, and further comprising at least two switches respectively controlled by separate phases of a second clock signal to apply current in alternation from the at least two storage capacitors of the switched-capacitor charge pump circuit to the inductive load; and

a control circuit that generates the one or more first clock signals and the second clock signal so that the second clock signal has a phase offset with respect to the one or more first clock signals that is set to adjust a conversion ratio of the circuit.

12. The circuit of claim 11 , wherein the switched-capacitor charge pump circuit comprises:

a first charge pump circuit comprising a first capacitor of the at least two storage capacitors and a first plurality of switches separate from the at least two switches and operated by first phases of the one or more first clock signals; and

a second charge pump circuit coupled in parallel with the first charge pump circuit and comprising a second capacitor of the at least two storage capacitors, wherein the second charge pump circuit further comprises a second plurality of switches separate from the at least two switches and operated by second phases of the one or more first clock signals that are complementary with the first phases of the one or more first clock signals, so that the second charge pump circuit operates in an opposite phase from the first charge pump circuit with respect to the one or more first clock signals.

13. The circuit of claim 12 , wherein the first charge pump circuit further comprises at least one third capacitor coupled to the first capacitor by at least one switch of the first plurality of switches, and wherein the second charge pump circuit further comprises at least one fourth capacitor coupled to the second capacitor by at least one switch of the first plurality of switches.

14. The circuit of claim 11 , wherein the inductive load is a speaker and wherein the control circuit controls the phase offset according to an audio signal representation, whereby the circuit implements an audio power amplifier.

15. The circuit of claim 14 , wherein the at least two switches include a pair of switches that intermittently couple a first terminal of the speaker to the at least two storage capacitors and a third switch that intermittently couples the first terminal of the speaker to a return voltage.

16. The circuit of claim 14 , wherein the switched-capacitor charge pump circuit is a first switched-capacitor charge pump circuit that implements a first side of a bridged audio power amplifier having an output coupled to the first terminal of the speaker, and wherein the circuit further comprises a second charge pump circuit that implements a second side of the bridged audio power amplifier and having an output coupled to a second terminal of the speaker.

17. The circuit of claim 14 , wherein the switched-capacitor charge pump circuit has an output coupled to a first terminal of the speaker, and wherein the second terminal of the speaker is coupled to a return terminal.

18. A method of delivering power to a load, comprising:

receiving an input voltage or current at an input terminal of a power supply circuit;

operating a switched-capacitor charge pump circuit according to one or more first clock signals to charge at least two storage capacitors of the switched-capacitor charge pump circuit in different phases of the one or more first clock signals; and

operating an inductor-based power supply circuit in cascade with the switched-capacitor charge pump circuit between the input terminal and an output terminal according to one or more second clock signals, wherein the one or more second clock signals have a phase offset with respect to the one or more first clock signals that is set to adjust a conversion ratio of the power delivery system.

19. The method of claim 18 , wherein the switched-capacitor charge pump circuit comprises at least two switches, and wherein the method further comprises controlling the at least two switches with separate phases of the one or more second clock signals to apply or receive inductor current in alternation between the at least two storage capacitors of the switched-capacitor charge pump circuit.

20. The method of claim 19 , wherein the switched-capacitor charge pump circuit comprises a pair of charge pump circuits coupled in parallel and operating in opposite phase with respect to the one or more first clock signals.

21. The method of claim 18 , wherein a duty cycle of the one or more first clock signals and a duty cycle of the one or more second clock signals are in a range between 40 and 60 percent.

22. The method of claim 19 , wherein the input terminal is a terminal that supplies a connection to a DC input voltage source through an external inductance, wherein the operating the switched-capacitor charge pump circuit operates the at least two switches of the switched-capacitor charge pump circuit to direct current from the external inductance to provide input current to the switched-capacitor charge pump circuit, and wherein the switched-capacitor charge pump circuit has an output coupled to the output terminal to deliver the power to the load.

23. The method of claim 18 , wherein the input terminal is coupled to an input of the switched-capacitor charge pump circuit, wherein an output of the charge pump is coupled to an input of the inductor-based power supply circuit, and wherein the output of the inductor-based power supply circuit has an output coupled to the output terminal to deliver the power to the load.

24. The method of claim 18 , wherein the method further comprises:

selecting between a first operating mode and a second operating mode;

responsive to selecting the first operating mode, transferring energy from the first terminal to the second terminal by the cascaded combination of the switched-capacitor charge pump circuit and the inductor-based power supply circuit; and

responsive to selecting the second operating mode, transferring energy from the second terminal to the first terminal by the cascaded combination of the switched-capacitor charge pump circuit and the inductor-based power supply circuit.

25. The method of claim 24 , wherein the first terminal is coupled to a battery that is discharged in the first operating mode and that is charged in the second operating mode.

26. A method of delivering power to an inductive load, comprising:

receiving an input voltage or current at a first terminal;

operating a switched-capacitor charge pump circuit according to one or more first clock signals to charge at least two storage capacitors of the switched-capacitor charge pump circuit in different phases of the one or more clock signals; and

operating the switched-capacitor charge pump circuit according to one or more second clock signals to direct charge from the at least two storage capacitors to apply current in alternation from the at least two storage capacitors of the switched-capacitor charge pump circuit to the load; and

generating the one or more first clock signals and the one or more second clock signals so that the one or more second clock signals have a phase offset with respect to the one or more first clock signals that is set to adjust a conversion ratio of the circuit.

27. The method of claim 26 , wherein the switched-capacitor charge pump circuit comprises a pair of charge pump circuits coupled in parallel and operating in opposite phase with respect to the one or more first clock signals.

28. The method of claim 26 , wherein the inductive load is a speaker and wherein the generating controls the phase offset according to an audio signal representation, whereby the method is a method of operation of an audio power amplifier.

29. The method of claim 28 , wherein the one or more second clock signals operate a pair of switches that intermittently couple a first terminal of the speaker to the at least two storage capacitors and a third switch that intermittently couples the first terminal of the speaker to a return voltage.

30. The method of claim 28 , wherein the switched-capacitor charge pump circuit is a first switched-capacitor charge pump circuit that implements a first side of a bridged audio power amplifier having an output coupled to the first terminal of the speaker, and wherein the method further comprises operating a second charge pump circuit that implements a second side of the bridged audio power amplifier and has an output coupled to a second terminal of the speaker.

31. The method of claim 28 , wherein the switched-capacitor charge pump circuit has an output coupled to a first terminal of the speaker, and wherein the second terminal of the speaker is coupled to a return terminal.