Charge pump circuit and methods of operation thereof

Patent metadata

Field	Value
Publication number	US-9917508-B2
Application number	US-201614988446-A
Country	US
Kind code	B2
Filing date	Jan 5, 2016
Priority date	Dec 22, 2006
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

A charge pump circuit, and associated method and apparatuses, for providing a split-rail voltage supply, the circuit having a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of said states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage and centered on the voltage at the common terminal.

First claim

What is claimed is:

1. A charge pump circuit comprising:
an input terminal for receiving an input voltage;
first and second output terminals for connection to respective first and second reservoir capacitors and for outputting respective positive and negative output voltages;
first and second flying capacitor terminals for connection to a first flying capacitor;
third and fourth flying capacitor terminals for connection to a second flying capacitor;
a switch network connected to said input terminal, a common terminal, said first and second output terminals and said first, second, third and fourth flying capacitor terminals;
a switch controller configured to control said switch network in a sequence of states so as to generate said positive and negative output voltages at said first and second output terminals respectively,
wherein said switch controller is operable to control the switch network to adopt a first state in which the first and second flying capacitor terminals are connected to the first and second output terminals respectively such that the first flying capacitor is connected between said first and second output terminals.

2. A charge pump circuit as claimed in claim 1 wherein in said first state the third and fourth flying capacitor terminals are also connected to the first and second output terminals respectively such that second flying capacitor is also connected between said first and second output terminals.

3. A charge pump circuit as claimed in claim 2 wherein in said second state the first and second flying capacitors are connected in series with one another and connected between the input terminal and a common terminal.

4. A charge pump circuit as claimed in claim 1 wherein the switch controller is further operable to control the switch network to adopt a second state in which said first and second flying capacitors are connected in series with one another and connected to the input terminal.

5. A charge pump circuit as claimed in claim 4 wherein in said second state the first, second, third and fourth flying capacitor terminals are disconnected from the first and second output terminals.

6. A charge pump circuit as claimed in claim 1 wherein the switch controller is further operable to control the switch network to adopt a third state in which the first and third flying capacitor terminals are connected together and the second and fourth flying capacitor terminals are connected together such that the first and second flying capacitors are connected in parallel with one another and the first, second, third and fourth flying capacitor terminals are disconnected from the input terminal and from the first and second output terminals.

7. A charge pump circuit as claimed in claim 1 wherein the switch controller is operable in a first mode of operation to control said switch network in a first sequence of states including said first state and is further operable in second mode of operation to control said switch network in a second, different, sequence of states.

8. A charge pump circuit as claimed in claim 7 wherein in said first mode of operation the positive and negative output voltages have a first magnitude and in the second mode of operation the positive and negative output voltages have a second, different, magnitude.

9. A charge pump circuit as claimed in claim 8 wherein the first magnitude is equal to half the magnitude of the input voltage.

10. A charge pump circuit as claimed in claim 1 wherein said switch network comprises:
a first switch for connecting the input terminal to the first flying capacitor terminal;
a second switch for connecting the first flying capacitor terminal to the first output terminal;
a third switch for connecting the first flying capacitor terminal to the third flying capacitor terminal;
a fourth switch for connecting the second flying capacitor terminal to the common terminal;
a fifth switch for connecting the second flying capacitor terminal to the third flying capacitor terminal;
a sixth switch for connecting the second flying capacitor terminal to the fourth flying capacitor terminal;
a seventh switch for connecting the fourth flying capacitor terminal to the common terminal; and
an eighth switch for connecting the fourth flying capacitor terminal to the second output terminal.

11. A charge pump circuit as claimed in claim 10 wherein, in the first state, the second switch, the sixth switch and the eighth switch are all closed.

12. A charge pump circuit as claimed in claim 10 wherein, in the first state, the first, third, fourth, fifth and seventh switches are all open.

13. A charge pump circuit as claimed in claim 1 wherein the circuit is configured to alter the sequence of states in response to the operating conditions of the charge pump circuit.

14. A charge pump circuit as claimed in claim 1 comprising a first reservoir capacitor connected to said first output terminal, a second reservoir capacitor connected to said second output terminal, a first flying capacitor connected between said first and second flying capacitor terminals and a second flying capacitor connected between said third and fourth flying capacitor terminals.

15. An electronic device comprising a charge pump circuit as claimed in claim 1 .

16. A charge pump circuit comprising:
an input terminal for receiving an input voltage;
first and second output terminals for connection to respective first and second reservoir capacitors and for outputting respective positive and negative output voltages;
first and second flying capacitor terminals for connection to a first flying capacitor;
third and fourth flying capacitor terminals for connection to a second flying capacitor;
a switch network connected to said input terminal, a common terminal, said first and second output terminals and said first, second, third and fourth flying capacitor terminals;
a switch controller for controlling said switch network, wherein:
said switch controller is operable to control the switch network to adopt a first state in which the first flying capacitor terminal is connected to the input terminal and the second flying capacitor terminal is connected to the third flying capacitor terminal; and
said switch controller is also operable to control the switch network to adopt a second state in which the first and second flying capacitor terminals or the third and fourth flying capacitor terminals are connected to the first and second output terminals respectively such that one of the first and second flying capacitors terminal is connected between the first and second output terminals.

17. A charge pump circuit as claimed in claim 16 wherein the switch controller is operable in a first mode of operation to control said switch network in a first sequence of states including said first state and said second state and is further operable in second mode of operation to control said switch network in a second, different, sequence of states.

18. A charge pump circuit as claimed in claim 17 wherein in said first mode of operation the positive and negative output voltages have a first magnitude and in the second mode of operation the positive and negative output voltages have a second, different, magnitude.

19. A charge pump circuit comprising:
an input for receiving an input voltage;
a first output for outputting a positive output voltage;
a second output for outputting a negative output voltage;
first and second flying capacitors;
a switch network operable in a plurality of different switching states; and
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Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Lesso John P

Classifications

• H02M2003/072

  Electricity · mapped topic

• H02M3/07 Primary

  using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} · CPC title

• H02M3/072

  adapted to generate an output voltage whose value is lower than the input voltage · CPC title