Charge injection for ultra-fast voltage control in voltage regulators

Patent metadata

Field	Value
Publication number	US-10152071-B2
Application number	US-201615356993-A
Country	US
Kind code	B2
Filing date	Nov 21, 2016
Priority date	Mar 18, 2016
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

This application relates to a circuit for generating an output voltage and regulating the output voltage to a target voltage. The circuit includes a switchable voltage divider circuit configured to generate a feedback voltage that is a variable fraction of the output voltage, an error amplifier stage configured to generate a control voltage on the basis of a reference voltage and the variable fraction of the output voltage, a buffer stage configured to generate the output voltage on the basis of the control voltage, and a charge injection circuit configured to inject charge at an intermediate node between the error amplifier stage and the buffer stage to thereby modify the control voltage generated by the error amplifier stage. The application further relates to a method of operating such circuit.

First claim

What is claimed is:

1. A circuit for generating an output voltage and regulating the output voltage to a target voltage, the circuit comprising:
a switchable voltage divider circuit configured to generate a voltage that is a variable fraction of the output voltage;
an error amplifier stage configured to generate a control voltage on the basis of a reference voltage and the variable fraction of the output voltage;
a buffer stage configured to generate the output voltage on the basis of the control voltage; and
a charge injection circuit configured to inject charge at an intermediate node between the error amplifier stage and the buffer stage to thereby modify the control voltage generated by the error amplifier stage,
wherein the charge injection circuit is configured to inject the charge at the intermediate node to quickly raise or lower the output voltage to the target voltage; and
wherein the charge injection circuit comprises:
a first capacitive element; and
a switching circuit configured to be switchable to a first configuration in which the first capacitive element is disconnected from the intermediate node and coupled between the output voltage and a first voltage level below the output voltage, and a second configuration in which the first capacitive element is coupled between the intermediate node and a second voltage level above the first voltage level.

2. The circuit according to claim 1 , wherein the charge injection circuit is configured to inject charge at the intermediate node in such a manner that the control voltage is lowered if the variable fraction of the output voltage is larger than the reference voltage and raised if the variable fraction of the output voltage is smaller than the reference voltage.

3. The circuit according to claim 1 , further comprising a control logic for periodically switching the switching circuit between the first configuration and the second configuration while the fraction of the output voltage is below the reference voltage.

4. The circuit according to claim 3 , wherein the switching circuit is further configured to be switchable to a third configuration in which the first capacitive element is disconnected from the intermediate node and coupled between the output voltage and the second voltage level, and a fourth configuration in which the first capacitive element is coupled between the intermediate node and the first voltage level.

5. The circuit according to claim 4 , wherein the control logic is further configured to periodically switch the switching circuit between the third configuration and the fourth configuration while the fraction of the output voltage is above the reference voltage.

6. The circuit according to claim 1 , wherein the switching circuit comprises:
a first switching element for switchably coupling a first terminal of the first capacitive element to the first voltage level;
a second switching element for switchably coupling the first terminal of the first capacitive element to the second voltage level;
a third switching element for switchably coupling a second terminal of the first capacitive element to the output voltage; and
a fourth switching element for switchably coupling the second terminal of the first capacitive element to the intermediate node.

7. The circuit according to claim 1 , further comprising a second capacitive element coupled between the intermediate node and a predetermined voltage level.

8. The circuit according to claim 7 , wherein a capacity of the second capacitive element is larger than a capacity of the first capacitive element by a factor of ten or more.

9. The circuit according to claim 1 , wherein the charge injection circuit comprises a controllable current source.

10. A method of generating an output voltage and regulating the output voltage to a target voltage, the method comprising:
generating a voltage that is a variable fraction of the output voltage in accordance with a control signal depending on a desired target voltage;
generating a control voltage on the basis of a reference voltage and the variable fraction of the output voltage;
buffering the control voltage to generate the output voltage; and
modifying the generated control voltage by means of charge injection,
wherein the charge injection is performed to quickly raise or lower the output voltage to the target voltage; and
wherein charge injection is performed using a first capacitive element and the method further comprises the steps of:
comparing the variable fraction of the output voltage to the reference voltage; and
if the fraction of the output voltage is below the reference voltage, periodically switching between a first configuration in which the first capacitive element is disconnected from a voltage level of the control voltage and coupled between the output voltage and a first voltage level below the output voltage, and a second configuration in which the first capacitive element is coupled between the voltage level of the control voltage and a second voltage level above the first voltage level.

11. The method according to claim 10 , wherein modifying the control voltage involves lowering the control voltage if the variable fraction of the output voltage is larger than the reference voltage and raising the control voltage if the variable fraction of the output voltage is smaller than the reference voltage.

12. The method according to claim 10 , further comprising the steps of:
if the fraction of the output voltage is above the reference voltage, periodically switching between a third configuration in which the first capacitive element is disconnected from the voltage level of the control voltage and coupled between the output voltage and the second voltage level, and a fourth configuration in which the first capacitive element is coupled between the voltage level of the control voltage and the first voltage level.

13. The method according to claim 10 , further comprising the steps of:
switching a first switching element that switchably couples a first terminal of the first capacitive element to the first voltage level;
switching a second switching element that switchably couples the first terminal of the first capacitive element to the second voltage level;
switching a third switching element that switchably couples a second terminal of the first capacitive element to the output voltage; and
switching a fourth switching element that switchably couples the second terminal of the first capacitive element to the voltage level of the control voltage.

14. The method according to claim 10 , wherein charge injection is performed by means of a controllable current source.

15. The method according to claim 11 , wherein the charge is injected at an intermediate node, and the method further comprises coupling a second capacitive element between the intermediate node and a predetermined voltage level.

16. The method according to claim 15 , wherein a capacity of the second capacitive element is larger than a capacity of the first capacitive element by a factor of ten or more.

17. A method of generating an output voltage and regulating the output voltage to a target voltage, the method comprising:
generating a voltage that is a variable fraction of the output voltage in accordance with a control signal depending on a desired target voltage;
generating a control voltage on the basis of a reference voltage and the variable fraction of the output voltage;
buffering the control voltage to generate the output voltage; and
modifying the generated control voltage by means of charge injection,
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Assignees

• Dialog Semiconductor Uk Ltd

Inventors

• Ciomaga Dan
• Jefremow Mihail
• Drebinger Stephan
• Rigoni Fabio

Classifications

• G05F1/562

  with a threshold detection shunting the control path of the final control device · CPC title

• G05F1/575 Primary

  characterised by the feedback circuit · CPC title

• G05F1/565

  sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor (G05F1/563 takes precedence) · CPC title