Voltage regulator with improved electrical properties and corresponding control method

Patent metadata

Field	Value
Publication number	US-2016349776-A1
Application number	US-201514969103-A
Country	US
Kind code	A1
Filing date	Dec 15, 2015
Priority date	May 27, 2015
Publication date	Dec 1, 2016
Grant date	—

Abstract

A voltage-regulator device includes an error-amplifier stage configured to receive a first reference voltage and a feedback voltage, an output amplifier stage coupled to the error-amplifier stage and configured to generate an output voltage related to the first reference voltage by an amplification factor, and a feedback stage configured to generate the feedback voltage. A compensation stage is configured to implement a second feedback loop, and cause, in response to a variation of the output voltage, a corresponding variation of a first biasing voltage for the output amplifier stage. The compensation stage includes a coupling-capacitor element coupled between the output amplifier stage and a first internal node, and a driving module coupled between the first internal node, and the output amplifier stage and configured to generate a compensation voltage for driving the output amplifier stage.

First claim

1 - 15 . (canceled)

16 . A voltage-regulator device comprising:
an error-amplifier stage having
first and second inputs configured to receive a first reference voltage and a feedback voltage, respectively, and
an output;
an output amplifier stage having
an input coupled to the output of said error-amplifier stage, and
an output configured to generate an output voltage related to the first reference voltage by an amplification factor;
a feedback stage coupled to the output of said output amplifier stage and configured to generate the feedback voltage based upon the output voltage for implementing a first feedback loop; and a compensation stage coupled between the output of said output amplifier stage and the input of said output amplifier stage, and configured to
implement a second feedback loop, and
cause, in response to a variation of the output voltage, a corresponding variation of a first biasing voltage for the input of said output amplifier stage,
said compensation stage comprising
a coupling-capacitor element coupled between the output of said output amplifier stage and a first internal node, and
a driving module having an input coupled to the first internal node, and an output coupled to the input of said output amplifier stage and configured to generate a compensation voltage for driving said output amplifier stage.

17 . The voltage-regulator device according to claim 16 wherein the output amplifier stage comprises:
an output transistor having first and second conduction terminals coupled between the output of said output amplifier stage and a supply voltage, and a control terminal coupled to the input of said output amplifier stage and configured to receive the first biasing voltage;
the compensation voltage configured to drive the control terminal.

18 . The voltage-regulator device according to claim 16 wherein said compensation stage is configured to implement a derivation circuit having a frequency response with at least one pole outside an operating frequency band of the voltage-regulator device, and a single zero; and wherein the second feedback loop has a greater response speed than the first feedback loop.

19 . The voltage-regulator device according to claim 18 wherein the voltage-regulator device has a frequency response with a dominant pole at the output of said error-amplifier stage, and at a frequency less than the at least one pole in the frequency response of said compensation stage.

20 . The voltage-regulator device according to claim 17 wherein said driving module is configured to enable, in response to variation of the output voltage, a current path towards the input of said output amplifier stage.

21 . The voltage-regulator device according to claim 20 wherein said driving module comprises a discharge transistor coupled to the input of said output amplifier stage and configured to implement the current path and supply the compensation voltage; and wherein said discharge transistor is configured in a voltage-follower mode.

22 . The voltage-regulator device according to claim 21 wherein said driving module further comprises an enabling transistor having a conduction terminal coupled to the first internal node, and a control terminal; and wherein said conduction terminal of said enabling transistor is configured to:
have a control voltage thereon, the control voltage having a variation corresponding to the output voltage; and
enable said discharge transistor to define the current path and determine extraction of current from said output amplifier stage.

23 . The voltage-regulator device according to claim 22 wherein said discharge transistor has first and second conduction terminals coupled between the input of said output amplifier stage and a second internal node, and a control terminal coupled to a third internal node; wherein said driving module further comprises:
a coupling transistor diode-coupled between the supply voltage and the third internal node; and
a first biasing transistor having first and second conduction terminals coupled between the second internal node and a second reference voltage, and a control terminal configured to receive a second biasing voltage;
wherein said discharge transistor and said first biasing transistor are configured to define the current path.

24 . The voltage-regulator device according to claim 23 wherein said driving module further comprises:
a second biasing transistor having first and second conduction terminals coupled between the third internal node and the first internal node, and a control terminal configured to receive a third biasing voltage; and
a third biasing transistor having first and second conduction terminals coupled between the second internal node and the control terminal of said enabling transistor, and a control terminal configured to receive the third biasing voltage.

25 . The voltage-regulator device according to claim 16 wherein said feedback stage is configured to generate the feedback voltage as a division of the output voltage.

26 . A voltage-regulator device comprising:
an error-amplifier stage configured to receive a first reference voltage and a feedback voltage; an output amplifier stage coupled to said error-amplifier stage, and configured to generate an output voltage related to the first reference voltage by an amplification factor; a feedback stage coupled to said output amplifier stage and configured to generate the feedback voltage based upon the output voltage for implementing a first feedback loop; and a compensation stage coupled in feedback with said output amplifier stage and configured to
implement a second feedback loop, and
cause, in response to a variation of the output voltage, a corresponding variation of a first biasing voltage for said output amplifier stage, said compensation stage comprising
a coupling-capacitor element coupled between said output amplifier stage and a first internal node, and
a driving module coupled between the first internal node, and said output amplifier stage and configured to generate a compensation voltage for driving said output amplifier stage.

27 . The voltage-regulator device according to claim 26 wherein the output amplifier stage comprises:
an output transistor having first and second conduction terminals coupled between an output of said output amplifier stage and a supply voltage, and a control terminal coupled to an input of said output amplifier stage and configured to receive the first biasing voltage;
the compensation voltage configured to drive the control terminal.

28 . The voltage-regulator device according to claim 26 wherein said compensation stage is configured to implement a derivation circuit having a frequency response with at least one pole outside an operating frequency band of the voltage-regulator device, and a single zero; and wherein the second feedback loop has a greater response speed than the first feedback loop.

29 . The voltage-regulator device according to claim 28 wherein the voltage-regulator device has a frequency response with a dominant pole at an output of said error-amplifier stage, and at a frequency less than the at least one pole in the frequency response of said compensation stage.

30 . The voltage-regulator device according to claim 27 wherein said driving module is configured to enable, in response to variation of the output voltage, a current path towards the input of said output amplifier stage.

31 . The voltage-regulator device according to claim 30 wherein said driving module comprises a discharge transistor coupl

Assignees

• St Microelectronics Srl

Inventors

• Conte Antonino
• Paolino Carmelo

Classifications

• H03F1/42

  Modifications of amplifiers to extend the bandwidth · CPC title

• H03F1/34

  Negative-feedback-circuit arrangements with or without positive feedback (H03F1/02 - H03F1/30, H03F1/38 - H03F1/50, H03F3/50 take precedence {; for rejection of common mode signals H03F3/45479}) · CPC title

• H02M3/07

  using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} · CPC title

• G05F1/575 Primary

  characterised by the feedback circuit · CPC title

• H03F3/45

  Differential amplifiers (differential sense amplifiers G11C7/062) · CPC title