Voltage regulator with improved tracking of a reference voltage

Patent metadata

Field	Value
Publication number	US-10164525-B2
Application number	US-201615574382-A
Country	US
Kind code	B2
Filing date	May 26, 2016
Priority date	May 28, 2015
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

There is disclosed a voltage regulator, including a switching stage, for generating an output voltage, the voltage regulator comprising a feedback path for controlling the switching stage, in which a feedback signal in the feedback path is ramp-compensated, the ramp for the ramp compensation being generated from an output of the switching stage.

First claim

The invention claimed is:

1. A voltage regulator comprising:
a switching stage;
an inductive element coupled between the switching stage and an output of the voltage regulator; and
a feedback path configured to control the switching stage, wherein the feedback path comprises:
an amplifier;
a first resistive element having a first terminal coupled to a first terminal of the inductive element;
a first capacitive element having a first terminal coupled to a second terminal of the inductive element, a second terminal of the first resistive element and a second terminal of the first capacitive element being coupled to a first input of the amplifier; and
a switch coupled between a second input of the amplifier and the second terminal of the inductive element.

2. The voltage regulator of claim 1 , wherein a feedback signal is generated by the feedback path to control the switching stage, the feedback signal being generated by applying a ramp compensation to a signal representing a current flowing to the output of the voltage regulator.

3. The voltage regulator of claim 2 , wherein
the signal representing the current flowing to the output of the voltage regulator is generated by measuring a voltage difference across the first capacitive element.

4. The voltage regulator of claim 1 , further comprising:
a second capacitive element having a first terminal connected to the second terminal of the inductive element; and
a second resistive element having a first terminal connected to a second terminal of the second capacitive element.

5. The voltage regulator of claim 4 , further comprising:
a feedback comparator having a first input connected to a connection point between the first resistive element and the first capacitive element, and having a second input connected to another connection point between the second capacitive element and the second resistive element, an output of the feedback comparator being connected to a control input of the switching stage.

6. The voltage regulator of claim 5 , wherein:
the switch is connected in parallel with the second capacitive element;
when the switch is closed, the feedback comparator is configured to generate, at the output of the feedback comparator, a feedback signal representing a current flowing across the inductive element; and
when the switch is open, the feedback comparator is configured to generate, at the output of the feedback comparator, a ramp compensated feedback signal.

7. The voltage regulator of claim 6 , wherein the switch is closed when the first terminal of the inductive element is connected to electrical ground via the switching stage, and the switch is open when the first terminal of the inductive element is connected to a voltage rail via the switching stage.

8. The voltage regulator of claim 1 , further comprising:
a first comparator configured to compare an output voltage of the voltage regulator with a reference voltage to provide a comparison voltage; and
a second comparator configured to compare the comparison voltage with a feedback signal generated by the feedback path and provide a control signal for the switching stage based on the comparison of the comparison voltage with the feedback signal.

9. The voltage regulator of claim 8 , further comprising:
a linear amplifier; and
a power amplifier, the power amplifier being configured to receive a signal to be amplified, and the linear amplifier being configured to receive an envelope of the signal to be amplified;
a third capacitive element connected between an output of the linear amplifier and the second terminal of the inductive element, wherein the second terminal of the inductive element is connected to a power supply input of the power amplifier; and
a third comparator connected in parallel with the third capacitive element and having an output connected to the first comparator, wherein the reference voltage is indicative of a desired voltage to be developed across the third capacitive element.

10. The voltage regulator of claim 4 , wherein a second terminal of the second resistive element is connected to electrical ground.

11. A method for voltage regulation, comprising:
generating a first signal representing a current flowing to an output of a voltage regulator, and a second signal having a slope that is based on an output voltage of the voltage regulator;
generating a feedback signal based on the first signal and the second signal; and
controlling a switching stage of the voltage regulator with the feedback signal to generate the output voltage.

12. The method of claim 11 , wherein the voltage regulator comprises:
an inductive element having a first terminal connected to the switching stage and a second terminal connected to the output of the voltage regulator;
a first resistive element having a first terminal connected to the first terminal of the inductive element; and
a first capacitive element having a first terminal coupled to the second terminal of the inductive element, a second terminal of the first resistive element and a second terminal of the first capacitive element being coupled together, the first signal being generated at the second terminal of the first capacitive element.

13. The method of claim 12 , wherein the voltage regulator further comprises:
a second capacitive element having a first terminal connected to the second terminal of the inductive element; and
a second resistive element having a first terminal connected to a second terminal of the second capacitive element, the method further comprising generating the second signal via the second capacitive element and the second resistive element.

14. The method of claim 13 , wherein the voltage regulator further comprises:
a feedback comparator having a first input connected to a connection point between the first resistive element and the first capacitive element, the method further comprising providing the second signal to a second input of the feedback comparator, the feedback signal being generated at an output of the feedback comparator.

15. The method of claim 14 , further comprising:
closing a switch connected in parallel with the second capacitor to generate another feedback signal representing the current flowing to the output of the voltage regulator, the switching stage being controlled via the other feedback signal when the switch is closed; and
opening the switch connected in parallel with the second capacitor to generate the feedback signal, the switching stage being controlled via the feedback signal when the switch is open.

16. The method of claim 15 , wherein the switch is closed when the first terminal of the inductive element is connected to electrical ground, and the switch is open when the first terminal of the inductive element is connected to a voltage rail.

17. The method of any one of claims 12 to 16 , further comprising:
comparing the output voltage with a reference voltage to provide a comparison voltage;
comparing the comparison voltage with the feedback signal; and
providing a control input to the switching stage based on the comparison of the comparison voltage with the feedback signal.

18. The method of claim 17 , further comprising:
receiving a signal to be amplified at an input of a power amplifier; and
receiving an envelope of the signal to be amplified at an input of a linear amplifier, wherein:
the voltage regulator comprises a third capacitive element connected between an output of the linear amplifier and the second terminal of the inductive element, wherein the second terminal

Assignees

• Snaptrack Inc

Inventors

• Labbe Benoit
• Wimpenny Gerard

Classifications

• H02M2001/0009

  Electricity · mapped topic

• H02M3/156 Primary

  with automatic control of output voltage or current, e.g. switching regulators · CPC title

• G05F1/56

  using semiconductor devices in series with the load as final control devices (G05F1/461 takes precedence) · CPC title

• H02M2001/0025

  Electricity · mapped topic

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title