Method and circuit for suppressing pop noise in an audio operation amplifier

Patent metadata

Field	Value
Publication number	US-9954494-B1
Application number	US-201615347799-A
Country	US
Kind code	B1
Filing date	Nov 10, 2016
Priority date	Oct 26, 2016
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A method for suppressing POP noise in an audio operation amplifier, comprising: connecting a first resistor and a second resistor in series at an output stage of the audio operation amplifier by turning on a first switch and a second switch; generating, with a ramp generator, a ramp voltage after an audio signal is input into the audio operation amplifier, wherein the ramp voltage varies from zero to a first value; generating, with an voltage generator, a second voltage, wherein a third switch is turned on and a fourth switch is turned off when the ramp voltage reaches the second value; short-circuiting the first and second resistors by turning off the first and second switches; and outputting, with the audio operation amplifier, an amplified audio signal.

First claim

What is claimed is:

1. An audio device, comprising:
an audio operation amplifier; and
a circuit for suppressing POP noise in the audio operation amplifier, comprising:
a first switch connected to a first resistor in parallel;
a second switch connected to a second resistor in parallel; and
the first resistor is configured to be connected in series to the second resistor at an output stage of the audio operation amplifier by turning on the first switch and the second switch simultaneously;

a ramp generator connected to the audio operation amplifier via a third switch and configured to generate a ramp voltage after an audio signal is input into the audio operation amplifier, wherein the ramp voltage varies from zero to a first value after the third switch is turned off;
a voltage generator connected to the audio operation amplifier via a fourth switch and configured to generate a second voltage, wherein the third switch is turned on and the fourth switch is turned off when the ramp voltage reaches a second value,
wherein the first and the second resistors further configured to be short-circuited by turning off the first and the second switches simultaneously, and the audio operation amplifier is further configured to output an amplified audio signal.

2. The audio device of claim 1 , wherein the first and the second resistors further configured to be connected in series at the output stage of the audio operation amplifier by turning on the first and the second switches when stopping inputting the audio signal, wherein the output of the audio operation amplifier changes from second to first value slowly;
the ramp voltage varies from the first value to zero after the third switch is turned off and the fourth switch is turned on; and
the audio operation amplifier further configured to be turned off.

3. The audio device of claim 1 , wherein the second voltage is a common-mode voltage.

4. The audio device of claim 3 , wherein a difference between value of the first value and the second value is smaller than 10 mV.

5. The audio device of claim 2 , wherein the output stage of the audio operation amplifier is a Class-AB output stage.

6. The audio device of claim 2 , wherein the audio operation amplifier is a multi-stage operation amplifier.

7. A method for suppressing POP noise in an audio operation amplifier, comprising:
connecting a first resistor and a second resistor in series at an output stage of the audio operation amplifier by turning on a first switch and a second switch simultaneously;
generating, with a ramp generator, a ramp voltage after an audio signal is input into the audio operation amplifier, wherein the ramp voltage varies from zero to a first value;
generating, with a voltage generator, a second voltage, wherein a third switch is turned on and a fourth switch is turned off when the ramp voltage reaches a second value;
short-circuiting the first and the second resistors by turning off the first and the second switches simultaneously; and
outputting, with the audio operation amplifier, an amplified audio signal.

8. The method of claim 7 , further comprising:
connecting the first resistor and the second resistor in series at an output stage of the audio operation amplifier by turning on the first and the second switches when stopping inputting the audio signal;
turning off the third switch and turning on the fourth switch, wherein the ramp voltage varies from the first value to zero; and
turning off the audio operation amplifier.

9. The method of claim 7 , wherein the second voltage is a common-mode voltage.

10. The method of claim 9 , wherein a difference between value of the first value and the second value is smaller than 10 mV.

11. The method of claim 8 , wherein the output stage of the audio operation amplifier is a Class-AB output stage.

12. The method of claim 8 , wherein the audio operation amplifier is a multi-stage operation amplifier.

Assignees

• Beken Corp

Inventors

• Gao Donghui
• Liu Jiazhou
• Guo Dawei

Classifications

• H03F3/21

  with semiconductor devices only {(H03F3/245 takes precedence)} · CPC title

• H03F1/0277

  Selecting one or more amplifiers from a plurality of amplifiers · CPC title

• H03F3/45179

  using MOSFET transistors as the active amplifying circuit (H03F3/45278 takes precedence) · CPC title

• H03F1/342 Primary

  in field-effect transistor amplifiers · CPC title

• H03F3/185

  with field-effect devices (H03F3/187 takes precedence) · CPC title