CLASS G AUDIO AMPLIFIERS AND ASSOCIATED METHODS OF OPERATION

• US 20110123048A1
• Filed: 10/20/2010
• Published: 05/26/2011
• Est. Priority Date: 10/20/2009
• Status: Active Grant

• Current Assignee: Monolithic Power Systems Incorporated
• Original Assignee: Monolithic Power Systems Incorporated
• Inventors: Wang, Rui, Zhang, Zhengwei, Wang, Haishi, Lin, Jinyan
• Granted Patent: US 8,605,915 B2
• Time in Patent Office: Days
• US Class Current: 381/120
• CPC Class Codes: H03F 1/0244 Stepped control
• CPC Class Codes: H03F 3/187 in integrated circuits
• CPC Class Codes: H03F 3/21 with semiconductor devices only H03F3/245 takes precedence
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

The present technology is directed to class G audio amplifiers and the associated methods of operation. In one embodiment, a class G audio amplifier includes an input port, an audio output stage, a level detector, and a charge pump. The class G audio amplifier regulates the power supplies of the audio output stage according to the input signal, so as to realize high efficiency and high quality audio output.

Claims

1. A class G audio amplifier, comprising:

an input port configured to receive an input signal;

an audio output stage coupled to the input port, wherein the audio output stage is configured to output an amplified audio signal that is based on the input signal;

a level detector coupled to the input port, wherein the level detector is configured to detect a level of the input signal and to output a detected level signal based on the detected level of the input signal;

a charge pump coupled to the level detector, wherein the charge pump is configured to provide a positive power supply voltage and a negative power supply voltage in response to the detected level signal, the positive power supply and the negative power supply being coupled to power the audio output stage.

2. The class G audio amplifier of claim 1, further comprising a speaker coupled to an output of the audio output stage.

3. The class G audio amplifier of claim 1, wherein the level detector detects an instantaneous voltage level of the input signal.

4. The class G audio amplifier of claim 1, wherein the level detector detects an amplitude of the input signal.

5. The class G audio amplifier of claim 1, wherein the positive power supply and the negative power supply have the same amplitude but opposite polarities from each other.

6. The class G audio amplifier of claim 1, wherein the charge pump is configured to operate at ±

1/N, ±

2/N, . . . , ±

(N−

2)/N, ±

(N−

1)/N, ±

½

x, ±

1×

mode, where N is a natural number.

7. The class G audio amplifier of claim 6, wherein during a transition from a high mode to a low mode, if an output of the charge pump is higher than a desired value, the charge pump is in a sleep mode.

8. The class G audio amplifier of claim 6, wherein when N=2, the charge pump comprises:

a power supply coupled to a positive output of the charge pump via a third switch;

a positive power capacitor coupled between the positive output of the charge pump and ground;

a negative power capacitor coupled between a negative output of the charge pump and ground;

a fly capacitor having

a first terminal controllably coupled to the power supply via a first switch, coupled to the positive output of the charge pump via a fourth switch, and coupled to ground via a second switch,

a second terminal controllably coupled to the positive output of the charge pump via a fifth switch, coupled to the negative output of the charge pump via a seventh switch, and coupled to ground via a sixth switch.

9. The class G audio amplifier of claim 8, wherein the first switch and the third switch operate as a controllable current source.

10. The class G audio amplifier of claim 8, wherein the fifth switch includes a diode.

11. The class G audio amplifier of claim 8, wherein the seventh switch includes diode.

12. The class G audio amplifier of claim 8, wherein when N=3, the fly capacitor includes a first fly capacitor and a second fly capacitor, wherein the first fly capacitor and the second fly capacitor are controllably coupled in series via a tenth switch, and controllably coupled in parallel via an eighth switch and a ninth switch.

13. A class G audio amplifier, comprising:

an input port for receiving an input signal;

means for providing an amplified audio signal in response to the input signal;

means for detecting a level of the input signal, and providing a detected level signal based on the detected level of the input signal;

means for providing a positive power supply and a negative power supply in response to the detected level signal, wherein the positive power supply and the negative power supply are coupled to power the means for providing the amplified audio signal.

14. The class G audio amplifier of claim 13, wherein the means for detecting the input signal detect an instantaneous voltage of the input signal.

15. The class G audio amplifier of claim 13, wherein the means for detecting the input signal detect an amplitude of the input signal.

16. The class G audio amplifier of claim 13, wherein the positive power supply and the negative power supply have the same amplitude but opposite polarities from each other.

17. The class G audio amplifier of claim 13, wherein the means for providing the positive power supply and the negative power supply operates at ±

1/N, ±

2/N, . . . , ±

(N−

2)/N, ±

(N−

1)/N, ±

½

×

, ±

1×

mode, where N is a natural number.

18. A method of operating a class G audio amplifier, comprising:

detecting a level of an input signal;

generating a detected level signal based on the detected level of the input signal;

providing a positive power supply and a negative power supply in response to the detected level signal;

producing an amplified audio signal in response to the input signal, the positive power supply, and the negative power supply.

19. The method in claim 18, wherein detecting the level of an input signal comprises detecting an amplitude of the input signal.

20. The method in claim 18, wherein detecting the level of an input signal comprises detecting an instantaneous voltage of the input signal.

21. The method in claim 18, wherein the positive power supply and the negative power supply have the same amplitude but opposite polarities from each other.

22. The method of claim 21 wherein providing the positive power supply and the negative power supply includes providing a positive power supply and a negative power supply with a voltage that is ±

V_DD/N, ±

2*V_DD/N, ±

3*V_DD/N, . . . , ±

(N−

2)*V_DD/N, ±

(N−

1)*V_DD/N, ±

V_DD, where V_DD is a voltage level of a general power supply, and N is a natural number.