High-efficiency DC/DC voltage converter including capacitive switching pre-converter and up inductive switching post-regulator

• US 20080157732A1
• Filed: 08/08/2007
• Published: 07/03/2008
• Est. Priority Date: 12/30/2006
• Status: Active Grant

• Current Assignee: Advanced Analogic Technologies Incorporated (Skyworks Solutions Incorporated)
• Original Assignee: Advanced Analogic Technologies Incorporated (Skyworks Solutions Incorporated)
• Inventors: Williams, Richard K.
• Granted Patent: US 7,812,579 B2
• Time in Patent Office: Days
• US Class Current: 323/266
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A DC/DC converter includes a pre-converter stage, which may include a charge pump, and a post-regulator stage, which may include a boost converter. The duty factor of the post-regulator stage is controlled by a feedback path that extends from the output terminal of the DC/DC converter to an input terminal in the post-regulator stage. The pre-converter steps the input DC voltage up or down by a positive or negative integral or fractional value, and the post-regulator steps the voltage up by a variable amount depending on the duty factor at which the post-regulator is driven. The converter overcomes the problems of noise glitches, poor regulation, and instability, even near unity input-to-output voltage conversion ratios.

Claims

1. A DC/DC voltage converter comprising:

a pre-converter comprising a switched capacitive circuit; and

a post-regulator comprising a switched inductive circuit,

wherein an output terminal of the pre-converter is coupled to an input terminal of the post-regulator, an input terminal of the pre-converter comprising an input terminal of the DC/DC voltage converter, an output terminal of the post-regulator comprising an output terminal of the DC/DC voltage converter.

2. The DC/DC voltage converter of claim 1 further comprising a feedback path, a first terminal of the feedback path being coupled to the input terminal of the pre-converter, a second terminal of the feedback path being coupled to the output terminal of the post-regulator.

4. The DC/DC voltage converter of claim 1 wherein the post-regulator comprises a high-side switch connected in a series path with a low-side switch and an inductor connected to a point in the series path between the high-side switch and the low-side switch.

5. The DC/DC voltage converter of claim 4 wherein the high-side switch comprises a high-side MOSFET and the low-side switch comprises a low-side MOSFET.

6. The DC/DC voltage converter of claim 5 wherein the post-regulator comprises a break-before-make unit coupled to a gate of the high-side MOSFET and a gate of the low-side MOSFET and a pulse width modulation unit coupled to the break-before-make unit.

8. The DC/DC voltage converter of claim 6 comprising a clock generator coupled to the pulse width modulation unit and to the pre-converter.

10. The DC/DC voltage converter of claim 6 wherein the post-regulator comprises a level shift unit coupled to the pulse width modulation unit.

11. The DC/DC voltage converter of claim 10 comprising a feedback path, a first terminal of the feedback path being coupled to the level shift unit.

12. The DC/DC voltage converter of claim 11 wherein a second terminal of the feedback path is coupled to the output terminal of the post-regulator.

13. The DC/DC voltage converter of claim 1 wherein the pre-converter comprises a charge pump, the charge pump producing an output voltage equal to a predetermined multiple of an input voltage.

14. The DC/DC voltage converter of claim 13 wherein the charge pump produces an output voltage equal to 0.5 times the input voltage.

15. The DC/DC voltage converter of claim 14 wherein the post-regulator comprises a boost converter.

16. The DC/DC voltage converter of claim 15 wherein the post-regulator comprises:

an inductor and a low-side MOSFET connected in a series conduction path being an output terminal of the pre-converter and ground; and

a synchronous rectifier MOSFET connected between a common node in the series conduction path between the inductor and the low-side MOSFET and the output terminal of the DC/DC converter.

17. The DC/DC voltage converter of claim 13 wherein the charge pump produces an output voltage equal to 2 times the input voltage.

18. The DC/DC voltage converter of claim 17 wherein the post-regulator comprises a boost converter.

19. The DC/DC voltage converter of claim 18 wherein the post-regulator comprises:

an inductor and a low-side MOSFET connected in a series conduction path being an output terminal of the pre-converter and ground; and

a synchronous rectifier MOSFET connected between a common node in the series conduction path between the inductor and the low-side MOSFET and the output terminal of the DC/DC converter.

20. The DC/DC voltage converter of claim 13 wherein the charge pump produces an output voltage equal to 1.5 times the input voltage.

21. The DC/DC voltage converter of claim 20 wherein the post-regulator comprises a boost converter.

22. The DC/DC voltage converter of claim 21 wherein the post-regulator comprises:

an inductor and a low-side MOSFET connected in a series conduction path being an output terminal of the pre-converter and ground; and

a synchronous rectifier MOSFET connected between a common node in the series conduction path between the inductor and the low-side MOSFET and the output terminal of the DC/DC converter.

23. The DC/DC voltage converter of claim 13 wherein the charge pump produces an inverted output voltage equal to −

1 times the input voltage.

24. The DC/DC voltage converter of claim 23 wherein the post-regulator comprises a non-inverting boost converter.

25. The DC/DC voltage converter of claim 23 wherein the post-regulator comprises an inverting boost converter.

26. The DC/DC voltage converter of claim 13 wherein the charge pump produces an inverted output voltage equal to −

0.5 times the input voltage.

27. The DC/DC voltage converter of claim 26 wherein the post-regulator comprises a non-inverting boost converter.

28. The DC/DC voltage converter of claim 26 wherein the post-regulator comprises an inverting boost converter.

3. (canceled)

7. (canceled)

9. (canceled)