High-efficiency DC/DC voltage converter including capacitive switching pre-converter and up 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 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.
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 DC/DC voltage converter comprising an input terminal of the pre-converter, an output terminal of the DC/DC voltage converter comprising an output terminal of the post-regulator, and wherein the post-regulator is structured to produce a voltage at the output terminal of the post-regulator that is higher in absolute value than the voltage at the input terminal of the post-regulator.
2. The DC/DC voltage converter of claim 1 wherein the post-regulator comprises a synchronous rectifier switch connected in a series path with a low-side switch and an inductor connected to a point in the series path between the synchronous rectifier switch and the low-side switch.
3. The DC/DC voltage converter of claim 2 wherein the synchronous rectifier switch comprises a synchronous rectifier MOSFET and the low-side switch comprises a low-side MOSFET.
4. The DC/DC voltage converter of claim 3 wherein the post-regulator comprises a break-before-make unit coupled to a gate of the synchronous rectifier MOSFET and a gate of the low-side MOSFET and a pulse width modulation unit coupled to the break-before-make unit.
5. The DC/DC voltage converter of claim 4 comprising a clock generator coupled to the pulse width modulation unit and to the pre-converter.
6. The DC/DC voltage converter of claim 4 wherein the post-regulator comprises a level shift unit coupled to the pulse width modulation unit.
7. The DC/DC voltage converter of claim 6 comprising a feedback path, a first terminal of the feedback path being coupled to the level shift unit.
8. The DC/DC voltage converter of claim 7 wherein a second terminal of the feedback path is coupled to the output terminal of the post-regulator.
9. The DC/DC voltage converter of claim 1 wherein the pre-converter comprises a charge pump, the charge pump being structured to produce an output voltage equal to a predetermined multiple of an input voltage.
10. The DC/DC voltage converter of claim 9 wherein the charge pump is structured to produce an output voltage equal to 1.5 times the input voltage.
11. The DC/DC voltage converter of claim 10 wherein the post-regulator comprises a boost converter.
12. The DC/DC voltage converter of claim 11 wherein the post-regulator comprises:
an inductor and a low-side MOSFET connected in a series conduction path between 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.
13. The DC/DC voltage converter of claim 9 wherein the charge pump is structured to produce a voltage at the output terminal of the pre-converter that is lower in absolute value than a voltage at the input terminal of the pre-converter.
14. The DC/DC voltage converter of claim 13 wherein the charge pump is structured to produce 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 between 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 9 wherein the charge pump is structured to produce 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 between 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 1 further comprising a feedback path, a first terminal of the feedback path being coupled to control circuitry of the post-regulator, a second terminal of the feedback path being coupled to the output terminal of the post-regulator.
21. 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 DC/DC voltage converter comprising an input terminal of the pre-converter, an output terminal of the DC/DC voltage converter comprising an output terminal of the post-regulator; and
wherein the pre-converter comprises a charge pump inverter.
22. The DC/DC voltage converter of claim 21 wherein the post-regulator comprises an inverting boost converter.
23. The DC/DC voltage converter of claim 21 wherein the charge pump inverter is structured to produce 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 21 wherein the charge pump inverter is structured to produce an inverted output voltage equal to −0.5 times the input voltage.
27. The DC/DC voltage converter of claim 21 wherein the post-regulator comprises a non-inverting boost converter.