Switched mode amplifier with single-ended buck mode

• US 9,577,587 B2
• Filed: 05/07/2015
• Issued: 02/21/2017
• Est. Priority Date: 05/08/2014
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Maru, Siddharth, King, Eric J.
• Primary Examiner(s): Bernardi, Brenda
• Application Number:
  US14/706,624
• Publication Number:
  US 20150326187A1
• Time in Patent Office: 656 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• CPC Class Codes: H02M 7/00 Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: H03F 1/0277 Selecting one or more amplifiers from a plurality of amplifiers
• CPC Class Codes: H03F 1/083 in transistor amplifiers H03F1/10 - H03F1/22 take precedence
• CPC Class Codes: H03F 2200/03 the amplifier being designed for audio applications
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 3/181 Low-frequency amplifiers, e.g. audio preamplifiers
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• CPC Class Codes: H03F 3/2178 using more than one switch or switching amplifier in parallel or in series H03F3/2173, H03F3/2175 take precedence

Abstract

A power converter may include a power inductor, a plurality of switches arranged to sequentially operate in a plurality of switch configurations, an output for producing the output voltage, wherein a first switch is coupled to a first output terminal of the output and a second switch is coupled to a second output terminal of the output, and a linear amplifier coupled to the output. The controller may be configured to, in a linear amplifier mode of the power stage, enable the linear amplifier to transfer electrical energy from an input source of the power stage to the load, and in at least one mode of the power stage other than the linear amplifier mode, sequentially apply switch configurations from the plurality of switch configurations to selectively activate or deactivate each of the plurality of switches in order to transfer the electrical energy from the input source to the load.

Claims

1. A switching power stage for producing an output voltage to a load, comprising:

a power converter comprising;

a power inductor;

a plurality of switches arranged to sequentially operate in a plurality of switch configurations in accordance with a selected operational mode of the power converter, the selected operational mode selected from a plurality of operational modes; and

an output for producing the output voltage comprising a first output terminal and a second output terminal, wherein a first switch of the plurality of switches is coupled to the first output terminal and a second switch of the plurality of switches is coupled to the second output terminal;

wherein the plurality of operational modes comprises a single-ended buck mode for switching a polarity of the output voltage in which;

during a charging phase of the power converter, at least one of the plurality of switches is activated such that the power inductor is coupled between a first terminal of a power source and a particular one of the first output terminal and the second output terminal;

during a transfer phase of the power converter, at least one of the plurality of switches is activated such that the power inductor is coupled between a second terminal of the power source and the particular one of the first output terminal and the second output terminal; and

the output voltage comprises a differential voltage between the first output terminal and the second output terminal; and

a controller configured to sequentially apply switch configurations from the plurality of switch configurations to selectively activate or deactivate each of the plurality of switches in order to transfer electrical energy from an input source of the power converter to the load in accordance with the selected operational mode and in order to generate a current of the power inductor based on an output signal of a modulator and the selected operational mode, in order to, for each of the plurality of operational modes, cause the power converter to convert the output signal of the modulator to the output voltage.

2. The switching power stage of claim 1, further comprising at least one of a capacitor coupled to the first output terminal and a capacitor coupled to the second output terminal, and wherein the first switch is coupled between the power inductor and the first output terminal and the second switch is coupled between the power inductor and the second output terminal.

3. The switching power stage of claim 1, wherein:

the single-ended buck mode comprises a first submode for increasing the output voltage and a second submode for decreasing the output voltage;

the particular one of the first output terminal and the second output terminal is the first output terminal in the first submode; and

the particular one of the first output terminal and the second output terminal is the the second output terminal in the second submode.

4. The switching power stage of claim 1, wherein the controller is configured to operate the power converter in the single-ended buck mode when at least one of a magnitude of the output voltage and a magnitude of a target voltage of the output voltage is below a threshold magnitude.

5. The switching power stage of claim 4, wherein the controller is configured to operate the power converter in a mode other than the single-ended buck mode when at least one of the magnitude of the output voltage and the magnitude of a target voltage of the output voltage is above the threshold magnitude.

6. The switching power stage of claim 4, wherein the threshold magnitude is approximately 1 volt.

7. The switching power stage of claim 1, wherein the load is an acoustic transducer.

8. The switching power stage of claim 1, wherein the controller controls switching of the plurality of switches to produce the output voltage as a function of an input signal.

9. The switching power stage of claim 8, wherein the input signal is an audio signal.

10. A method for producing an output voltage to a load, comprising:

in a power converter comprising a power inductor, a plurality of switches arranged to sequentially operate in a plurality of switch configurations in accordance with a selected operational mode of the power converter selected from a plurality of operational modes, and an output for producing the output voltage comprising a first output terminal and a second output terminal, wherein a first switch of the plurality of switches is coupled to the first output terminal and a second switch of the plurality of switches is coupled to the second output terminal, sequentially applying a plurality of switch configurations to selectively activate or deactivate each of the plurality of switches in order to;

operate the power converter in a single-ended buck mode for switching a polarity of the output voltage, such that;

during a charging phase of the power converter, at least one of the plurality of switches is activated such that the power inductor is coupled between a first terminal of a power source and a particular one of the first output terminal and the second output terminal; and

during a transfer phase of the power converter, at least one of the plurality of switches is activated such that the power inductor is coupled between a second terminal of the power source and the particular one of the first output terminal and the second output terminal;

the output voltage comprises a differential voltage between the first output terminal and the second output terminal; and

a current of a power inductor of the power converter is generated based on an output signal of a modulator and the particular mode, in order to, for each of the plurality of operational modes, cause the power converter to convert the output signal of the modulator to the output voltage.

11. The method of claim 10, wherein the power converter comprises at least one of a capacitor coupled to the first output terminal and a capacitor coupled to the second output terminal, and wherein the first switch is coupled between the power inductor and the first output terminal and the second switch is coupled between the power inductor and the second output terminal.

12. The method of claim 10, wherein:

the single-ended buck mode comprises a first submode for increasing the output voltage and a second submode for decreasing the output voltage;

the particular one of the first output terminal and the second output terminal is the first output terminal in the first submode; and

the particular one of the first output terminal and the second output terminal is the the second output terminal in the second submode.

13. The method of claim 10, further comprising operating the power converter in the single-ended buck mode when at least one of a magnitude of the output voltage and a magnitude of a target voltage of the output voltage is below a threshold magnitude.

14. The method of claim 13, further comprising operating the power converter in a mode other than the single-ended buck mode when at least one of the magnitude of the output voltage and the magnitude of a target voltage of the output voltage is above the threshold magnitude.

15. The switching power stage of claim 13, wherein the threshold magnitude is approximately 1 volt.

16. The method of claim 10, wherein the load is an acoustic transducer.

17. The method of claim 10, further comprising controlling switching of the plurality of switches to produce the output voltage as a function of an input signal.

18. The method of claim 10, wherein the input signal is an audio signal.