Rectifier circuit for monitoring dc offset of a single-supply audio power amplifier

Patent metadata

Field	Value
Publication number	US-9648420-B2
Application number	US-201615164404-A
Country	US
Kind code	B2
Filing date	May 25, 2016
Priority date	Mar 24, 2014
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

An audio power amplifier arrangement includes an audio power amplification integrated circuit having two loudspeaker outputs. A rectifier circuit includes a first diode having a cathode connected to one of the two loudspeaker outputs and an anode connected to a rectifier output node. A second diode has an anode connected to the one loudspeaker output. A first resistor has a first end connected to a cathode of the second diode and a second end connected to the rectifier output node. A capacitor has a first end connected to the rectifier output node and a second end connected to electrical ground. A second resistor has a first end connected to the rectifier output node and a second end connected to electrical ground.

First claim

What is claimed is:

1. An audio power amplifier arrangement, comprising:
an audio power amplification circuit having two loudspeaker outputs;
a first diode having a cathode connected to one of the two loudspeaker outputs and an anode connected to a rectifier output node;
a second diode having an anode connected to the one loudspeaker output;
a first resistor having a first end connected to a cathode of the second diode and a second end connected to the rectifier output node;
a capacitor having a first end connected to the rectifier output node and a second end connected to electrical ground; and
a second resistor having a first end connected to the rectifier output node and a second end connected to electrical ground.

2. The arrangement of claim 1 further comprising a microcontroller connected to the rectifier output node.

3. The arrangement of claim 2 wherein the microcontroller includes an integral analog-to-digital converter.

4. The arrangement of claim 2 wherein the microcontroller is configured to place the audio power amplification circuit in a low power stand by mode in response to detecting that a voltage at the rectifier output node is above a threshold level.

5. The arrangement of claim 4 wherein the threshold level is above two Volts.

6. The arrangement of claim 1 further comprising a comparator circuit connected to the rectifier output node.

7. The arrangement of claim 1 wherein a value of the capacitor is approximately between two microfarads and ten microfarads, and a value of the first resistor is approximately between 100,000 ohms and 200,000 ohms.

8. An audio power amplifier arrangement, comprising:
an audio power amplification circuit having a loudspeaker output;
a first diode having a cathode connected to the loudspeaker output and an anode connected to a rectifier output node;
a second diode having an anode connected to the loudspeaker output;
a resistor having a first end connected to a cathode of the second diode and a second end connected to the rectifier output node;
a capacitor having a first end connected to the rectifier output node and a second end connected to electrical ground; and
means for detecting that a voltage at the rectifier output node is above a threshold level.

9. The arrangement of claim 8 further comprising means for removing voltage from the loudspeaker output in response to the detecting means detecting that the voltage at the rectifier output node is above the threshold level.

10. The arrangement of claim 9 wherein the removing means comprises a microcontroller.

11. The arrangement of claim 8 wherein the resistor comprises a first resistor, the rectifier circuit further comprising a second resistor having a first end connected to the rectifier output node and a second end connected to electrical ground.

12. The arrangement of claim 8 wherein the detecting means comprises a microcontroller.

13. The arrangement of claim 12 wherein the microcontroller includes an integral analog-to-digital converter.

14. The arrangement of claim 8 wherein the detecting means comprises a comparator circuit.

15. A method of processing an audio signal, comprising the steps of:
inputting the audio signal into a power amplification circuit having a power amplification circuit output;
connecting a rectifier circuit to the power amplification circuit output, the rectifier circuit including:
a first diode having a cathode connected to the output and an anode connected to a rectifier output;
a second diode having an anode connected to the power amplification circuit output;
a resistor having a first end connected to a cathode of the second diode and a second end connected to the rectifier output; and
a capacitor having a first end connected to the rectifier output and a second end connected to electrical ground; and
detecting that a voltage at the rectifier output is above a threshold level.

16. The method of claim 15 comprising the further step of removing voltage from the power amplification circuit output in response to the detecting that the voltage at the rectifier output is above the threshold level.

17. The method of claim 15 wherein the resistor comprises a first resistor, the rectifier circuit further comprising a second resistor having a first end connected to the rectifier output and a second end connected to electrical ground.

18. The method of claim 15 comprising the further step of placing the power amplification circuit in a low power stand by mode in response to the detecting that the voltage at the rectifier output is above the threshold level.

19. The method of claim 15 comprising the further step of muting an associated audio channel in response to the detecting that the voltage at the rectifier output is above the threshold level.

20. The method of claim 19 comprising the further steps of:
charging the capacitor through the second diode and the resistor; and
discharging the capacitor through the first diode.

Assignees

• Panasonic Automotive Systems Co America Division Of Panasonic Corp North America

Inventors

• Hickerson Dallas Dwight
• Finlon Kenneth Dale

Classifications

• H04R2499/13

  Acoustic transducers and sound field adaptation in vehicles · CPC title

• H03F3/185

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

• H04R3/12

  for distributing signals to two or more loudspeakers {(specially adapted for hearing aids H04R25/407)} · CPC title

• H03F3/45475

  using IC blocks as the active amplifying circuit · CPC title

• H04R3/007 Primary

  Protection circuits for transducers · CPC title