Systems and methods for switching and mixing signals in a multi-channel amplifier

• US 7,929,718 B1
• Filed: 05/12/2004
• Issued: 04/19/2011
• Est. Priority Date: 05/12/2003
• Status: Expired due to Fees

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: D2Audio LLC (Renesas Electronics Corporation)
• Inventors: Hand, Larry E., Gephardt, Douglas D., Andersen, Jack B.
• Primary Examiner(s): Chin; Vivian
• Assistant Examiner(s): MONIKANG, GEORGE C
• Application Number:
  US10/843,852
• Time in Patent Office: 2,533 Days
• Field of Search: 381 57- 59, 381/120, 381/123, 381/118, 381/119, 700/94, 341/143
• US Class Current: 381/120
• CPC Class Codes: H03F 3/217 Class D power amplifiers; Switching amplifiers
• 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

Systems and methods for scaling the number of output channels that can be provided in an audio amplification system. In one embodiment, a digital pulse width modulation (PWM) amplification system includes multiple four-channel PWM controller chips that are interconnected to enable synchronization and transfer of digital audio data from one chip to another. Input audio signals received by each of the channels are processed by sample rate converters to generate internal audio signals that have a predetermined sample rate and format. Each of the channels is synchronized so that the internal audio signal of each channel can be processed and output by any of the other channels. The PWM controller chips are connected by a high-speed interconnect that enables the transfer of data between them. Each input audio signal can be mapped to any of the outputs and can be mixed with other input signals.

Claims

1. A system comprising:

a plurality of audio amplifier channels each including

a sample rate converter (SRC),

a pulse width modulation (PWM) modulator downstream of the SRC, and

an output stage downstream of the PWM modulator, and

wherein each of the audio amplifier channels is configured

to receive a corresponding digital audio signal having a corresponding sample rate, and

to use the SRC of the audio amplifier channel to convert the corresponding digital audio signal to a common predetermined digital data format having a common predetermined sample rate; and

a data transport medium coupled to each of the audio amplifier channels downstream of the SRCs of the plurality of audio amplifier channels;

wherein the SRCs are configured to cause all the digital audio signals downstream of the SRCs in the plurality of audio amplifier channels to have the common predetermined digital data format having the common predetermined sample rate even when the sample rates of the plurality of the digital audio signals upstream of the SRCs differ from one another;

wherein the data transport medium is configured to transmit digital audio signals in the common predetermined digital data format having the common predetermined sample rate from one or more of the audio amplifier channels to one or more others of the audio amplifier channels;

wherein one or more of the audio amplifier channels is also configured

to receive, via the data transport medium, audio signals in the common predetermined digital data format having the common predetermined sample rate from one or more of the other audio amplifier channels,

to select one or more of the audio signals in the common predetermined digital data format having the common predetermined sample rate, and

to provide an output signal based on the one or more selected audio signals.

2. The system of claim 1, wherein the data transport medium comprises a matrix switch.

3. The system of claim 1, wherein the data transport medium comprises a bus.

4. The system of claim 3, wherein the bus is configured to transport the digital audio data in a time division multiplexed manner.

5. The system of claim 1, further comprising control logic configured to control transport of the audio signals in the predetermined digital data format between one or more of the audio amplifier channels.

6. The system of claim 5, wherein the control logic is internal to one or more of the audio amplifier channels.

7. The system of claim 5, wherein the control logic is external to the audio amplifier channels.

8. The system of claim 1, wherein the audio amplifier channels are implemented in a plurality of separate chips.

9. The system of claim 8, further comprising a synchronization system configured to synchronize ones of the audio amplifier channels implemented in different chips.

10. The system of claim 1, wherein each of the audio amplifier channels further comprises an audio effects processor.

11. The system of claim 10, wherein each of the audio amplifier channels further comprises a PWM modulator.

12. The system of claim 11, wherein the sample rate converter, audio effects processor and PWM modulator are implemented in a PWM controller.

13. The system of claim 1, wherein each of the audio amplifier channels comprises a digital PWM amplifier channel.

14. The system of claim 1, wherein one or more of the audio amplifier channels is configured to generate a composite audio signal based on at least two of the selected audio signals and to provide the composite audio signal as the output signal.

15. The system of claim 1, wherein each of the audio amplifier channels is configured to receive the corresponding audio signal at an input sample rate which is unknown, to estimate the input sample rate, and to convert the corresponding audio signal from the input sample rate to a predetermined digital data format.

16. The system of claim 1, wherein the data transport medium is configured to provide the audio signals from each of the audio amplifier channels to all of the other audio amplifier channels.

17. The system of claim 1, wherein the data transport medium comprises a matrix switch that is configured to transmit the audio signal from all of the audio amplifier channels to any one of the other audio amplifier channels.

18. The system of claim 1, wherein each of the audio amplifier channels comprises an input portion and an output portion, wherein each of the audio amplifier channels is controllable to provide at the corresponding output portion a signal received at any one of the input portions of the other audio amplifier channels.

19. The system of claim 2, wherein the matrix switch has N inputs and N outputs, where N is an integer equal to a number of audio amplifier channels are in the plurality of audio amplifier channels.

20. The system of claim 1, wherein the data transport medium is coupled to each of the audio amplifier channels upstream of the output stages of the plurality of audio amplifier channels.

21. A method comprising:

receiving digital audio signals in a plurality of audio amplifier channels, each of the digital audio signals having a corresponding sample rate, with the corresponding sample rate of one of the digital audio signals received in one of the audio amplifier channels differing from the corresponding sample rate of another one of the digital audio signals received in another one of the audio amplifier channels;

converting the digital audio signals received in all of the plurality of audio amplifier channels to a single predetermined digital format having a single predetermined sample rate, so that all the digital audio signals downstream of the converting in the plurality of audio amplifier channels have the common predetermined digital data format having the common predetermined sample rate even when the sample rates of the digital audio signals received in the plurality of audio amplifier channels differ from one another;

transmitting the converted digital audio signals from at least a first one of the audio amplifier channels to a second one of the audio amplifier channels;

in the second one of the audio amplifier channels, selecting at least one audio signal from the transmitted, converted digital audio signals and a locally converted audio signal; and

the second one of the audio amplifier channels processing the selected at least one audio signal to generate a corresponding output audio signal.

22. The method of claim 21, further comprising synchronizing the audio amplifier channels.

23. The method of claim 22, wherein synchronizing the audio amplifier channels comprises synchronizing a plurality of chips containing the audio amplifier channels.

24. The method of claim 21, wherein at least two audio signals are selected and are processed to form a composite output audio signal.

25. The method of claim 21, wherein the converted audio signals from at least a first one of the audio amplifier channels are transmitted to a second one of the audio amplifier channels via a matrix switch.

26. The method of claim 21, wherein the converted audio signals from at least a first one of the audio amplifier channels are transmitted to a second one of the audio amplifier channels via a bus.

27. The method of claim 21, wherein the converted audio signals from at least a first one of the audio amplifier channels are transmitted to a second one of the audio amplifier channels in a time division multiplexed manner.

28. The method of claim 21, wherein transmitting the converted audio signals from at least a first one of the audio amplifier channels to a second one of the audio amplifier channels is controlled by logic external to a chip containing the audio amplifier channels.

29. The method of claim 21, wherein transmitting the converted audio signals from at least a first one of the audio amplifier channels to a second one of the audio amplifier channels is controlled by logic internal to a chip containing the audio amplifier channels.

30. The method of claim 21, wherein the second one of the audio amplifier channels processing the selected at least one audio signal to generate the corresponding output audio signal comprises pulse-width modulating the at least one audio signal.

31. The method of claim 21, wherein the second one of the audio amplifier channels processing the selected at least one audio signal to generate the corresponding output audio signal comprises performing audio effects processing on the at least one audio signal.

32. The method of claim 21, further comprising selectively controlling each of the audio amplifier channels to produce an output audio signal corresponding to selected ones of the received audio signals.

33. The method of claim 21, wherein receiving the audio signals in the plurality of audio amplifier channels comprises receiving the audio signals at a plurality of different sample rates.

34. A system comprising:

a plurality of audio amplifier channels each including

a sample rate converter (SRC),

a pulse width modulation (PWM) modulator downstream of the SRC, and

an output stage downstream of the PWM modulator, and

wherein each of the audio amplifier channels is configured

to receive a corresponding digital audio signal having a corresponding sample rate, and

to use the SRC of the audio amplifier channel to convert the corresponding digital audio signal to a common predetermined digital data format having a common predetermined sample rate; and

a matrix switch coupled to each of the audio amplifier channels downstream of the SRCs of the plurality of audio amplifier channels;

wherein the SRCs are configured to cause all the digital audio signals downstream of the SRCs in the plurality of audio amplifier channels to have the common predetermined digital data format having the common predetermined sample rate even when the sample rates of the plurality of the digital audio signals upstream of the SRCs differ from one another; and

wherein the matrix switch is configured to transmit digital audio signals in the common predetermined digital data format having the common predetermined sample rate from one or more of the audio amplifier channels to one or more others of the audio amplifier channels.

35. The system of claim 34, wherein one or more of the audio amplifier channels is also configured to:

receive, via the matrix switch, audio signals in the common predetermined digital data format having the common predetermined sample rate from one or more of the other audio amplifier channels;

select one or more of the audio signals in the common predetermined digital data format having the common predetermined sample rate; and

provide an output signal based on the one or more selected audio signals.

36. The system of claim 34, wherein the matrix switch is coupled to each of the audio amplifier channels upstream of the output stages of the plurality of audio amplifier channels.