Buck voltage converter

Patent metadata

Field	Value
Publication number	US-10193449-B2
Application number	US-201715633098-A
Country	US
Kind code	B2
Filing date	Jun 26, 2017
Priority date	Jun 26, 2017
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

A buck voltage converter is provided which is configured so that a dominant pole of an open loop transfer function of the buck voltage converter is a pole introduced by a network comprising an inductor and a capacitor coupled to an output of the buck voltage converter.

First claim

What is claimed is:

1. A buck voltage converter, comprising:
a voltage input terminal,
a voltage output terminal,
a switch arrangement coupled to the voltage input terminal, the switch arrangement comprising a switch controller,
a feedback loop coupled between the voltage output terminal and the switch controller, and
a network comprising an inductor and a capacitor coupled to the voltage output terminal,
wherein the buck voltage converter is configured so that a dominant pole of an open loop transfer function of the buck voltage converter is a pole introduced by the network and wherein, apart from the dominant pole, each pole of the open loop transfer function having a frequency below a 0 dB crossing frequency of an open loop gain of the buck voltage converter has an associated zero having a frequency below the 0 dB crossing frequency of the open loop gain.

2. The buck voltage converter of claim 1 ,
wherein the dominant pole is a double complex conjugate pole introduced by the network.

3. The buck voltage converter of claim 1 ,
wherein the open loop transfer function further comprises at least one further zero in addition to a zero associated with the network to reduce a phase decrease caused by the dominant pole.

4. The buck voltage converter of claim 3 ,
wherein the feedback loop comprises an error amplifier having a high pass filter characteristic,
wherein the at least one further zero is introduced by the error amplifier.

5. The buck voltage converter of claim 4 , wherein the error amplifier comprises a differential input transistor pair, a first current mirror coupled to the differential input transistor pair and a second current mirror coupled to a node between the differential input transistor pair and the first current mirror, wherein the second current mirror is a source degenerated current mirror.

6. The buck voltage converter of claim 1 , wherein the switch controller is configured to control the switch arrangement based on a constant frequency pulse width modulation scheme.

7. The buck voltage converter of claim 1 , wherein the buck voltage converter is configured to operate in a voltage mode.

8. A buck voltage converter, comprising:
a voltage input terminal,
a voltage output terminal,
a voltage converter circuit coupled between the voltage input terminal and the voltage output terminal, wherein the voltage converter circuit comprises:
a switch arrangement;
an error amplifier having a high pass filter characteristic, wherein a first input of the error amplifier is configured to be coupled to a reference voltage, wherein a second input of the error amplifier is coupled to the voltage output terminal, and wherein an output of the error amplifier is coupled to the switch arrangement; and
a network comprising a capacitor and an inductor coupled to the voltage output terminal,
wherein the high pass filter characteristic of the error amplifier causes at least one zero of an open loop transfer function of the buck voltage converter to at least partially compensate a phase shift by a pole of the open loop transfer function introduced by the network, wherein the pole introduced by the network is a dominant pole of the open loop transfer function, and wherein, apart from the dominant pole, each pole of the open loop transfer function having a frequency below a 0 dB crossing frequency of an open loop gain of the buck voltage converter has an associated zero having a frequency below the 0 dB crossing frequency of the open loop gain.

9. The buck voltage converter of claim 8 , further comprising a resistive divider coupled between the voltage output terminal and the second input of the error amplifier, and a capacitor coupled in parallel to at least one resistor of the resistive divider.

10. The buck voltage converter of claim 9 , wherein the resistive divider is configured to introduce a pole and a zero in an open loop transfer function of the buck voltage converter below the zero dB crossing frequency of the open loop gain.

11. The buck voltage converter of claim 8 , wherein the switch arrangement comprises:
a comparator, wherein a first input of the comparator is coupled to the output of the error amplifier,
a signal generator circuit coupled to a second input of the comparator,
a high-side driver and a low-side driver, an input of the high-side driver and an input of the low-side driver being coupled to an output of the comparator,
a high-side switch coupled to the high-side driver, and
a low-side switch coupled to the low-side driver.

12. The buck voltage converter of claim 8 , further comprising:
a further voltage converter circuit coupled between the voltage input terminal and the voltage output terminal, wherein the voltage converter circuit and the further voltage converter circuit have different efficiencies depending on an output load.

13. The buck voltage converter of claim 8 , wherein the error amplifier comprises a differential input transistor pair, a first current mirror coupled to the differential input transistor pair and a second current mirror coupled to a node between the differential input transistor pair and the first current mirror, wherein the second current mirror is a source degenerated current mirror.

14. A method, comprising:
providing a voltage input terminal,
providing a voltage output terminal,
providing a switch arrangement between the voltage input terminal and the voltage output terminal,
coupling a network including an inductor and a capacitor to the voltage output terminal, providing a feedback loop between the voltage output terminal and a switch controller of the switch arrangement, and
configuring a buck voltage converter including the switch arrangement, the network and the feedback loop such that a dominant pole of an open loop transfer function of the buck voltage converter is introduced by the network, wherein, apart from the dominant pole, each pole of the open loop transfer function having a frequency below a 0 dB crossing frequency of an open loop gain of the buck voltage converter has an associated zero having a frequency below the 0 dB crossing frequency of the open loop gain.

15. The method of claim 14 ,
wherein providing the feedback loop comprises providing an error amplifier having a high pass filter characteristic.

16. The method of claim 14 ,
wherein providing the feedback loop comprises providing a capacitor coupled in parallel to at least one resistor of a resistive divider.

Assignees

• Infineon Technologies Ag

Inventors

• Biziitu Florin
• Pottbaecker Ansgar

Classifications

• H02M3/158

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M3/1588 Primary

  comprising at least one synchronous rectifier element (H02M3/1582, H02M3/1584 take precedence) · CPC title

• H02P8/12

  Control or stabilisation of current · CPC title

• G05F1/577

  for plural loads · CPC title

• H02M3/33507

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title