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Digital signal routing circuit

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20120300960 patent thumbnailZoom

Digital signal routing circuit


An integrated circuit for digital signal routing. Signal routing is achieved by means of a multiply-accumulate block, which takes data from one or more data source and, after any required scaling, generates output data for a data destination. The multiply-accumulate block operates on a time division multiplexed basis, so that multiple signal paths can be processed within one period of the sample clock. Each signal path has a respective sample clock rate, and paths with different sample clock rates can be routed through the multiply-accumulate block on a time division multiplexed basis independently of each other. Thus, speech signals at 8 kHz or 16 kHz can be processed concurrently with audio data at 44 kHz or 48 kHz.

Inventors: Graeme Gordon Mackay, Jonathan Timothy Wigner, Gordon Richard McLeod
USPTO Applicaton #: #20120300960 - Class: 381119 (USPTO) - 11/29/12 - Class 381 
Electrical Audio Signal Processing Systems And Devices > With Mixer



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The Patent Description & Claims data below is from USPTO Patent Application 20120300960, Digital signal routing circuit.

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This application claims the benefit of U.S. Provisional Application No. 61/491,041, filed May 27, 2011, the entire disclosure of which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a signal routing circuit, and in particular to a signal routing circuit that can be used as a digital audio hub, for interconnecting various signal sources and signal destinations in consumer devices, of which smartphones are just one example.

2. Description of the Related Art

It is known to provide an integrated circuit that acts as an “audio hub”, which is able to receive a number of signals from analog and digital sources, converting the analog signals to digital signals and then combining or processing the signals in the digital domain, in order to generate output signals. If required, the output signals can be converted by the audio hub into analog signals, in order to be applied to analog transducers such as headphones or speakers. Such a digital audio hub device can be incorporated into a consumer device, such as a smartphone or the like, allowing the received signals to be processed in predetermined ways.

It is desirable to allow the customer of the “audio hub” integrated circuit to use it to interconnect a number of different signal processing components within a consumer device in a flexible manner, without being restricted to specific external devices or to specific processing paths.

The invention is defined by the claims appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how it may be out into effect, reference will now be made, by way of example, to the accompanying drawings, in which:—

FIG. 1 shows a mobile telephone and various peripheral devices;

FIG. 2a shows components of the audio processing circuitry in the mobile telephone of FIG. 1;

FIG. 2b shows components of the audio processing circuitry in an alternative mobile telephone;

FIG. 3 is a first more detailed block diagram, showing the form of the audio hub routing circuitry in the audio processing circuitry of FIG. 2a or 2b;

FIG. 4 is a still more detailed block diagram, showing the form of the pre-conditioning circuitry in the routing circuitry of FIG. 3;

FIG. 5 is a further still more detailed block diagram, showing the form of the switching circuitry in the routing circuitry of FIG. 3;

FIG. 6 is a further still more detailed block diagram, showing an alternative form of the switching circuitry in the routing circuitry of FIG. 3;

FIG. 7 is a further still more detailed block diagram, showing the form of the down-sampling circuitry in the routing circuitry of FIG. 3;

FIG. 8 is a further still more detailed block diagram, showing the form of the up-sampling circuitry in the routing circuitry of FIG. 3;

FIG. 9 is a further still more detailed block diagram, showing the form of the post-conditioning circuitry in the routing circuitry of FIG. 3;

FIG. 10 is a further still more detailed block diagram, showing the form of the digital mixing core in the routing circuitry of FIG. 3;

FIG. 11 shows in more detail a part of a functional block in the digital mixing core of FIG. 10;

FIG. 12 shows in more detail a part of another functional block in the digital mixing core of FIG. 10;

FIG. 13 shows in more detail a part of a further functional block in the digital mixing core of FIG. 10;

FIG. 14 is a further block diagram, showing the digital mixing core of FIG. 10, and showing more detail of the functional blocks;

FIG. 15 is a block diagram, illustrating a different aspect of the digital mixing core in one embodiment;

FIG. 16 is a block diagram, illustrating the different aspect of the digital mixing core in another embodiment;

FIG. 17 is a block diagram, illustrating the different aspect of the digital mixing core in a further embodiment;

FIG. 18 is a block diagram, illustrating the different aspect of the digital mixing core in a still further embodiment;

FIG. 19 is a block diagram, illustrating the different aspect of the digital mixing core in a still further embodiment;

FIG. 20 is a block diagram, illustrating a part of the digital mixing core in one embodiment;

FIG. 21 is a block diagram, illustrating a part of the digital mixing core in another embodiment;

FIG. 22 is a block diagram, illustrating a form of a multiply-accumulate block in the digital mixing core;

FIG. 23 is a block diagram, illustrating in more detail an alternative form of the multiply-accumulate block in the digital mixing core;

FIG. 24 is a flow chart, illustrating a process performed in the mixer;

FIG. 25 is a further illustration of the process shown in FIG. 24;

FIG. 26 is a first timing diagram, illustrating the process of FIG. 24;

FIG. 27 is a second timing diagram, illustrating more detail of the process of FIG. 26;

FIG. 28 is a third timing diagram, illustrating a further alternative process;

FIG. 29 is a fourth timing diagram, illustrating a still further alternative process;

FIG. 30 is a flow chart, illustrating a method of defining the operation of the switching circuitry; and

FIG. 31 is a representation of a computer screenshot, illustrating a stage in the method of FIG. 30;

FIG. 32 is a block diagram, showing the routings in a use case defined by the process of FIG. 30;

FIG. 33 is a register map, illustrating an initial state of the register bank in the process of FIG. 30;

FIG. 34 is a block diagram, providing an alternative illustration of the routings in the use case of FIG. 32 on the digital mixing core of FIG. 14;

FIG. 35 is a register map, illustrating a state of the register bank at a further point in the process of FIG. 30;

FIG. 36 is a representation of the digital mixing core, showing the functional blocks involved in the use case shown in FIG. 32;

FIG. 37a shows a routing in a further use case;

FIG. 37b shows a routing in a still further use case;

FIG. 38 is a timing diagram, illustrating a first series of calculations in a process carried out in the mixer;

FIG. 39 is a timing diagram, illustrating a second series of calculations in a process carried out in the mixer;

FIG. 40 is a timing diagram, illustrating a third series of calculations in a process carried out in the mixer;

FIG. 41 is a timing diagram, illustrating a fourth series of calculations in a process carried out in the mixer;

FIG. 42 is a timing diagram, illustrating a fifth series of calculations in a process carried out in the mixer;

FIG. 43 is a block diagram, illustrating a clock generator in the switching circuit;

FIG. 44 is a block diagram, illustrating a further aspect of the clock generator;

FIG. 44a is a block diagram, illustrating an alternative form of the clock generator;

FIG. 44b is a block diagram, illustrating a further alternative form of the clock generator;

FIG. 44c is a block diagram, illustrating a further aspect of the alternative forms of the clock generator;

FIG. 45 is a block diagram, illustrating a mixer according to one embodiment;

FIG. 46 is a flow chart, illustrating a first method performed in the mixer of FIG. 45;

FIG. 47 is a flow chart, illustrating a second method performed in the mixer of FIG. 45;

FIG. 48 is a flow chart, illustrating a third method performed in the mixer of FIG. 45;

FIG. 49 is a block diagram, illustrating in more detail the enable and clock control block of the mixer of FIG. 45;

FIG. 50 is a flow chart, illustrating a method performed in the enable and clock control block of FIG. 49;

FIG. 51 is a flow chart, illustrating a further method performed in the enable and clock control block of FIG. 49;

FIG. 52a is a block diagram, illustrating in more detail the channel scheduler in the mixer of FIG. 45;

FIG. 52b is a flow chart, illustrating a method performed in the channel scheduler of FIG. 52a;

FIG. 53 is a flow chart, illustrating a further method performed in the channel scheduler of FIG. 52a;

FIG. 54 is a block diagram, illustrating in more detail the calculation block of the mixer of FIG. 45;

FIG. 55 is a flow chart, illustrating a part of the method performed in the channel scheduler block of FIG. 52a and calculation block of FIG. 54;

FIG. 56 is a schematic diagram, illustrating a part of an electronic device according to an aspect of the invention;

FIG. 57 is a schematic diagram, illustrating a part of a second electronic device according to an aspect of the invention;

FIG. 58 is a schematic diagram, illustrating a part of a third electronic device according to an aspect of the invention;

FIG. 59 is a schematic diagram, illustrating a part of a fourth electronic device according to an aspect of the invention;

FIG. 60 is a schematic diagram, illustrating a part of a fifth electronic device according to an aspect of the invention; and

FIG. 61 is a schematic diagram, illustrating a part of a sixth electronic device according to an aspect of the invention.

DETAILED DESCRIPTION

OF THE INVENTION

FIG. 1 shows a consumer device according to an aspect of the invention, in this example a mobile telephone 1, more specifically in the form of a smartphone. In this example, the mobile telephone 1 has a screen 3 and a keypad 5, although of course the invention is equally applicable to devices with touchscreens or other user interfaces. The mobile telephone 1 also has an inbuilt speaker 7 and an inbuilt main microphone 9, which are both analog transducers. The mobile telephone 1 also has a plurality of, in this particular example four, microphones 11 (which may be analog or digital microphones), allowing multiple ambient noise signals to be received, for example for use in a noise cancellation system.

As shown in FIG. 1, the mobile telephone 1 can have a jack socket (not illustrated) or similar connection means, such as a USB socket or a multi-pin connector socket, allowing a headset, comprising a pair of stereo earpieces 13 and possibly a microphone 15, to be connected to it by wire. Alternatively, the mobile telephone 1 can be connected wirelessly, for example using the Bluetooth (trade mark) communications protocol, to a wireless headset 17, having earpieces 19 and possibly a microphone 21. Although not illustrated, the earpieces 13, 19 may comprise one or more ambient noise microphones (which may be analog or digital microphones), allowing one or more ambient noise signals to be received, for example for use in a noise cancellation system.

Alternatively, or additionally, the mobile telephone 1 can have a socket or similar connection means allowing it to be connected to an external audio system 23 for music playback for example, the system comprising one or more speakers 25. The external audio system 23 might for example be a tabletop stereo sound system or an in-car audio system. Circuitry 27 of the external audio system 23 can include a radio receiver or other audio source, which may provide an audio input to the mobile telephone 1, so that the radio or other audio can be played back through the speaker 7 or through the earpieces 13, 19 of a selected one of the headsets. Alternatively, music stored on the phone can be played back through the speakers 25 of the external audio system 23.

It can thus be seen that there are many possible audio signals that can be output. For example, if the mobile telephone 1 has a connector allowing it to be fitted into a docking station in a motor vehicle and is equipped with a satellite navigation system, the mobile telephone 1 might need to be able simultaneously to: (a) handle a mobile telephone conversation via either the wired or the wireless handset; (b) provide stereo music from its memory to the external audio system 23; and (c) provide tones for confirmation of button presses and provide navigation instructions via the inbuilt speaker. Consequently, switching circuitry in the mobile telephone 1 must, according to the above example, be able to handle at least these three separate output audio data signals, as well as the input audio data signal of the mobile telephone conversation.

FIG. 2a shows components of the audio handling system in the mobile telephone 1. Communication with the cellular telephone network 29 is handled by a baseband processor (sometimes referred to as a communications processor) 31. An applications processor 33 handles, amongst other processes, processes in which audio data is reproduced from or stored into a memory 35 (which may be solid-state or on a disk, and which may be built-in or attachable, for example, either permanently in the mobile telephone or on a removable memory device) and other processes in which audio data is generated internally within the telephone 1. For example, the applications processor 33 may handle the reproduction of stereo music stored digitally in the memory 35, may handle recording of telephone conversations and other audio data into the memory 35, and will also handle the generation of satellite navigation commands and the generation of tones to confirm the pressing of any button on the keypad 5. A wireless transceiver (or wireless codec) 37 handles communications using the Bluetooth (trade mark) protocol or another short-range communications protocol, for example with the wireless headset 17.

The baseband processor 31, the applications processor 33, and the wireless transceiver 37 all send audio data to, and receive audio data from, switching circuitry in the form of an audio hub 39. The audio hub 39 takes the form of an integrated circuit in this described embodiment. In the embodiment described above, the audio signals between the audio hub 39 and the baseband processor 31, the applications processor 33, and the wireless transceiver 37 are all digital, and some of them may be in stereo, comprising a left data stream and a right data stream. Additionally, at least in the case of communication with the applications processor 33, further data streams may be multiplexed into the audio signals, for example to enable the applications processor 33 to provide stereo music and also other audio signals such as key press confirmation tones simultaneously.

The audio hub 39 communicates with the baseband processor 31, the applications processor 33, and the wireless transceiver 37 over respective audio data links, i.e. buses, 38b, 38a, 38c, and the audio hub 39 has respective digital interfaces 40b, 40a, 40c for these data links.

The audio hub 39 also provides audio signals to, and receives audio signals from, the built-in analog audio transducers of the mobile telephone 1. As shown in FIG. 2, the audio hub 39 provides output audio signals to the speaker 7, and receives input audio signals from the microphones 9, 11.

The audio hub 39 can also be connected to other output transducers 43, which may be analog or digital transducers, and which may be built in to the mobile telephone 1 (for example in the case of a haptic output transducer) or in devices external to the mobile telephone 1 (for example the earpieces 13 of the wired headset shown in FIG. 1). The audio hub 39 can also be connected to other input transducers 45, which again may be analog or digital transducers, and which again may be built in to the mobile telephone 1 (for example an ultrasound microphone) or in devices external to the mobile telephone 1 (for example the microphone 15 of the wired headset).

The audio hub 39 may also be required to receive signals from other sources such as an FM radio receiver 41, which may be in the external audio system 23, or may be provided on a separate IC in the mobile telephone 1, and which may generate either analog or digital signals.

It is to be appreciated that FIG. 2 shows just one possible use of the audio hub 39, whereas audio hub integrated circuits in accordance with the invention are usable in an extremely wide range of electronic devices, including industrial, professional or consumer devices, such as cameras (DSC and/or video), portable media players, PDAs, games consoles, satellite navigation devices, tablets, notebook computers, TVs or the like.

An audio hub integrated circuit can be optimised for one particular category out of a wide range of industrial, professional or consumer devices. For example, while FIG. 1 shows one particular form of smartphone 1, it will be appreciated that other smartphone models will have different levels of functionality, and will therefore have different audio handling requirements, and the audio hub integrated circuit can be designed to be able to handle this wide range of requirements. As described below, the audio hub 39 is optimised for use in smartphones, but is able to be used in a wide range of smartphones having different audio handling requirements.



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stats Patent Info
Application #
US 20120300960 A1
Publish Date
11/29/2012
Document #
13481403
File Date
05/25/2012
USPTO Class
381119
Other USPTO Classes
International Class
04B1/00
Drawings
62


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Electrical Audio Signal Processing Systems And Devices   With Mixer