Charge pump system capable of stabilizing an output voltage

• US 8,692,608 B2
• Filed: 09/19/2011
• Issued: 04/08/2014
• Est. Priority Date: 09/19/2011
• Status: Active Grant

• Current Assignee: United Microelectronics Corporation
• Original Assignee: United Microelectronics Corporation
• Inventors: Chen, Chien-Liang
• Primary Examiner(s): Hiltunen, Thomas J
• Application Number:
  US13/236,590
• Publication Number:
  US 20130069711A1
• Time in Patent Office: 932 Days
• Field of Search: 327/536, 363 59- 60
• US Class Current: 327/536
• CPC Class Codes: H02M 1/0003 Details of control, feedback or regulation circuits
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps

Abstract

A charge pump system includes a charge pump, a ring oscillator, a comparing circuit and a discharge circuit. When an output voltage of the charge pump is relatively low, the comparing circuit turns on the ring oscillator to make the ring oscillator provide an oscillation output to the charge pump to raise the output voltage of the charge pump. When the output voltage of the charge pump is relatively high, the comparing circuit turns off the ring oscillator to stop the ring oscillator from providing the oscillation output to the charge pump, the comparing circuit also makes the discharge circuit provide a discharge path to the charge pump to quickly reduce the output voltage of the charge pump.

Claims

1. A charge pump system comprising:

a charge pump comprising an output end for providing an output voltage;

a ring oscillator comprising an output end coupled to a control end of the charge pump for providing an oscillation output to the charge pump;

a comparing circuit comprising;

a first impedance having a first end coupled to the output end of the charge pump;

a second impedance having a first end coupled to a second end of the first impedance, and a second end coupled to ground; and

a comparator comprising;

a first input end coupled to the second end of the first impedance;

a second input end for receiving a reference voltage; and

an output end; and

a discharge circuit comprising;

a first switch having a first end directly coupled to the output end of the charge pump, and a control end coupled to the output end of the comparator;

a second switch having a first end coupled to a second end of the first switch, and a second end coupled to the ground; and

a third impedance having a first end coupled to the output end of the charge pump, and a second end coupled to a control end of the second switch.

2. The charge pump system of claim 1, wherein the first input end of the comparator is a positive input end, the second input end of the comparator is a negative input end, and the first switch is an NMOS transistor.

3. The charge pump system of claim 1, wherein the first input end of the comparator is a negative input end, the second input end of the comparator is a positive input end, and the first switch is a PMOS transistor.

4. The charge pump system of claim 1, wherein the second switch is an NMOS transistor.

5. The charge pump system of claim 1, wherein the output end of the comparator is coupled to an input end of the ring oscillator.

6. The charge pump system of claim 1, wherein the first impedance and the second impedance are resistors.

7. The charge pump system of claim 1, wherein the first impedance and the second impedance are capacitors.

8. The charge pump system of claim 1, wherein the first impedance and the second impedance are NMOS transistors, and a drain of each NMOS transistor is coupled to a source of the NMOS transistor.

9. The charge pump system of claim 1, wherein the first impedance and the second impedance are PMOS transistors, and a drain of each PMOS transistor is coupled to a source of the PMOS transistor.

10. The charge pump system of claim 1, wherein the third impedance is a resistor.

11. The charge pump system of claim 1, wherein the third impedance is a capacitor.

12. The charge pump system of claim 1, wherein the third impedance is a diode.

13. The charge pump system of claim 1, further comprising a fourth impedance having a first end coupled to the second end of the third impedance, and a second end coupled to the ground.

14. The charge pump system of claim 13, wherein the third impedance and the fourth impedance are resistors.

15. The charge pump system of claim 13, wherein the third impedance and the fourth impedance are capacitors.

16. The charge pump system of claim 13, wherein the third impedance and the fourth impedance are diodes.

17. A charge pump system comprising:

a charge pump comprising an output end for providing an output voltage;

a ring oscillator comprising an output end coupled to a control end of the charge pump for providing an oscillation output to the charge pump;

a comparing circuit comprising;

a first impedance having a first end directly coupled to a bias voltage source;

a second impedance having a first end coupled to a second end of the first impedance, and a second end coupled to the output end of the charge pump; and

a comparator comprising;

a first input end coupled to the second end of the first impedance;

a second input end for receiving a reference voltage; and

an output end; and

a charge circuit comprising;

a first switch having a first end directly coupled to the bias voltage source;

a second switch having a first end coupled to a second end of the first switch, a control end coupled to the output end of the comparator, and a second end coupled to the output end of the charge pump; and

a third impedance having a first end coupled to a control end of the first switch, and a second end coupled to the output end of the charge pump.

18. The charge pump system of claim 17, wherein the first input end of the comparator is a negative input end, the second input end of the comparator is a positive input end, and the second switch is an NMOS transistor.

19. The charge pump system of claim 17, wherein the first input end of the comparator is a positive input end, the second input end of the comparator is a negative input end, and the second switch is a PMOS transistor.

20. The charge pump system of claim 17, wherein the first switch is a PMOS transistor.

21. The charge pump system of claim 17, wherein the output end of the comparator is coupled to an input end of the ring oscillator.

22. The charge pump system of claim 17, wherein the first impedance and the second impedance are resistors.

23. The charge pump system of claim 17, wherein the first impedance and the second impedance are capacitors.

24. The charge pump system of claim 17, wherein the first impedance and the second impedance are NMOS transistors, and a drain of each NMOS transistor is coupled to a source of the NMOS transistor.

25. The charge pump system of claim 17, wherein the first impedance and the second impedance are PMOS transistors, and a drain of each PMOS transistor is coupled to a source of the PMOS transistor.

26. The charge pump system of claim 17, wherein the second end of the third impedance is coupled to the output end of the charge pump.

27. The charge pump system of claim 17, wherein the third impedance is a resistor.

28. The charge pump system of claim 17, wherein the third impedance is a capacitor.

29. The charge pump system of claim 17, wherein the third impedance is a diode.

30. The charge pump system of claim 17, further comprising a fourth impedance having a first end coupled to the bias voltage source, and a second end coupled to the first end of the third impedance.

31. The charge pump system of claim 30, wherein the third impedance and the fourth impedance are resistors.

32. The charge pump system of claim 30, wherein the third impedance and the fourth impedance are capacitors.

33. The charge pump system of claim 30, wherein the third impedance and the fourth impedance are diodes.