High-efficiency DC/DC voltage converter including capacitive switching pre-converter and down inductive switching post-regulator
View Patent ↗A DC/DC converter includes a pre-converter stage, which may include a charge pump, and a post-regulator stage, which may include a Buck 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 down 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.
1. A DC/DC voltage converter comprising:
a pre-converter comprising a switched capacitive circuit, the switched capacitive circuit comprising at least one capacitor, a terminal of the at least one capacitor being coupled through a first switch to an input terminal of the pre-converter and through a second switch to a reference voltage; 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 DC/DC voltage converter comprises the input terminal of the pre-converter, and an output terminal of the DC/DC voltage converter comprises an output terminal of the post-regulator; and
wherein the post-regulator is adapted to produce a voltage at the output terminal of the post-regulator that is lower in absolute value than a voltage at the input terminal of the post-regulator.
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 pre-converter, a second terminal of the feedback path being coupled to the output terminal of the post-regulator.
3. 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, a first terminal of the inductor being coupled to a point in the series path between the high-side switch and the low-side switch, the series path extending from the input terminal of the post-regulator.
4. The DC/DC voltage converter of claim 3 wherein a second terminal of the inductor is coupled to the output terminal of the post-regulator.
5. The DC/DC voltage converter of claim 3 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.
7. The DC/DC voltage converter of claim 6 wherein the post-regulator comprises a pulse width modulation unit coupled to the break-before-make unit and a clock generator coupled to the pulse width modulation unit.
8. The DC/DC voltage converter of claim 7 wherein the clock generator is coupled to the pre-converter.
9. The DC/DC voltage converter of claim 7 comprising a level shift unit coupled to the pulse width modulation unit.
10. The DC/DC voltage converter of claim 9 comprising a feedback path, a first terminal of the feedback path being coupled to the level shift unit.
11. The DC/DC voltage converter of claim 10 wherein a second terminal of the feedback path is coupled to the output terminal of the post-regulator.
12. A DC/DC voltage converter comprising:
a pre-converter, the pre-converter comprising a charge pump, the charge pump producing an output voltage equal to a predetermined multiple of an input voltage;
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 DC/DC voltage converter comprises an input terminal of the pre-converter, and an output terminal of the DC/DC voltage converter comprises an output terminal of the post-regulator; and
wherein the post-regulator is adapted to produce a voltage at the output terminal of the post-regulator that is lower in absolute value than a voltage at the input terminal of the post-regulator.
13. The DC/DC voltage converter of claim 12 wherein the predetermined multiple is a fraction less than one.
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 Buck converter.
16. The DC/DC voltage converter of claim 15 wherein the post-regulator comprises a high-side switch connected in a series path with a low-side switch and an inductor, a first terminal of the inductor being coupled to a point in the series path between the high-side switch and the low-side switch, the series path extending from the input terminal of the post-regulator.
17. The DC/DC voltage converter of claim 15 wherein a second terminal of the inductor is coupled to the output terminal of the post-regulator.
18. The DC/DC voltage converter of claim 12 wherein the predetermined multiple is a number greater than one.
19. The DC/DC voltage converter of claim 18 wherein the charge pump produces an output voltage equal to 2 times the input voltage.
20. The DC/DC voltage converter of claim 19 wherein the post-regulator comprises a Buck converter.
21. The DC/DC voltage converter of claim 20 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, the series path extending from the input terminal of the post-regulator.
22. The DC/DC voltage converter of claim 18 wherein the charge pump produces an output voltage equal to 1.5 times the input voltage.
23. The DC/DC voltage converter of claim 22 wherein the post-regulator comprises a boost converter.
24. The DC/DC voltage converter of claim 23 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, the series path extending from the input terminal of the post-regulator.
25. The DC/DC voltage converter of claim 12 wherein the predetermined multiple is a negative number.
26. The DC/DC voltage converter of claim 25 wherein the charge pump produces an inverted output voltage equal to −1 times the input voltage.
27. The DC/DC voltage converter of claim 25 wherein the charge pump produces an inverted output voltage equal to −0.5 times the input voltage.