2009-09-01  CONEXANT

CONEXANT’s new Speakers-on-a-Chip (SPoC) product family offers the world’s first solution to integrate an audio/voice processor, dual audio codec and Class-D amplifier in a single, cost-effective package. The family of devices offers a number of specialized, application-dependent functions and options. In addition, each of the new chip versions is designed for full duplex hands-free speakerphone functionality with acoustic echo cancellation across the entire audio frequency range (thus surpassing TIA 920 requirements), as well as noise reduction (NR) via hardware DSP. The combination of high-quality music playback and hands-free speakerphone functionality was made possible due to recent innovations in all-CMOS mixed-signal and DSP technologies. SPoC ICs also incorporate numerous functions that help reduce OEM manufacturing costs and power consumption, while at the same time allowing for customized adaptations. Because all functions have been combined within a single chip, product designs which have to date required multi-chip solutions are now significantly easier to implement. As a result, manufacturers can also expect faster development times for cost-effective “convergence products” that target high-definition audio and voice applications.

Ultimately, these new SPoC solutions incorporate the technology needed for easily combining audio meeting entertainment industry standards and high-quality voice communications in a single solution.

USB SPoC: CX20562

The CX20562 is the first member of the SPoC family. The device targets applications with an existing USB connection and is optimized for high-fidelity stereo sound with a 24-bit DAC. The CX20562 won first prize in the category Application-Specific Standard Products at the 2008 EDN Innovation Awards and also reached the final elimination stage for the Best Semiconductor Product at the 2009 TechAmerica High-Tech Innovations Awards.

The chip integrates complex DSP algorithms for high audio and voice quality. Among its core innovations are BrightSound, a proprietary audio processing algorithm that significantly improves audio quality when source sound levels are low, while also preventing speakers from overdriving. The algorithm combines dynamic range compression and equalization techniques to deliver “bright” and natural sounding audio. In addition, it incorporates a night mode that functions to preserve background signal quality when watching a video or playing PC games. Thus, the listener can still clearly hear spoken audio without turning up the volume and possibly disturbing others.  Using a stereo microphone and its unique DSP-based directional microphone technology it is possible to filter out background noise and improve audio quality during VoIP calls.

The CX20562 supports digital and analog volume control, as well as microphone and speaker muting. It incorporates many features for enhanced consumer value, including music-on-hold and a fade-in/fade-out effect for the AUX input, while furthermore offering GSM noise immunity and a quick-launch capability for Instant Messaging.

The new device has a single USB interface which allows manufacturers to develop PC and MAC-compatible plug-and-play (PnP) products addressing the following operating systems: Windows Vista, XP, SP2, 2K; Linux; and Mac OS X. The analog AUX input provides ease of connection for diverse audio devices, while the multimedia version of the chip also supports the connection of a 20-key keypad and an LCD display. The CX20562 delivers its full performance regardless whether it is powered via the USB bus or externally. The built-in Class-D amplifier delivers a 1.2W audio output signal that may also be used as a pre-amp stage for a power amplifier, thus making the CX20562 ideally suited for hand-held applications.

Target Applications:
- Speaker systems for all-in-one PCs
- LCD monitors with built-in speakers and hands-free speakerphone functionality
- Hands-free speakerphone systems
- Docking stations for laptops
- MP3 player docking stations with hands-free functionality
- USB hands-free speakerphones for VoIP applications
- Applications for the embedded USB market

The CX20562 is offered in three different versions and comes in a 48-pin Quad Flat No-Lead (QFN) package.

SPoC for Mono Hands-Free Applications: CX20662

The CX20662 is a mono version of the new SPoC family that also delivers full duplex hands-free speakerphone functionality with acoustic echo cancellation (AEC) across the entire audio frequency range. It supports analog line-in/line-out connections and can thus be conveniently integrated with virtually any type of audio system. Thanks to this design simplification, hands-free speakerphone functionality can be easily and cost-effectively implemented in a wide variety of products, regardless of the controller used.

In addition to the mentioned functionality that it shares with the CX20562, the CX20662 features line echo suppression (LES), programmable microphone boost, a hybrid circuit for intercom applications, voice activity detection, speech-trained AEC, a UART MCU interface and a driver for the direct connection of headphones. It is also equipped with a mono 600mW Class-D amplifier.

Target Applications:
- Intercom and door speakerphone systems
- Full duplex hands-free applications in telephones and phone systems
- Webcams with hands-free functionality
- Embedded audio applications with extended temperature range requirements

The CX20662 comes in a 40-pin Quad Flat No-Lead (QFN) package and is optionally available with an extended operating temperature range.

SPoC for Mono Hands-Free Speakerphones and Stereo Music Playback: CX20663

The CX20663 builds on the CX20662 by adding the capability for stereo music playback. In addition, it features programmable microphone boost, voice activity detection, speech-trained AEC and a UART MCU interface, while also integrating a stereo Class-D amplifier with 2*600mW.

The CX20663 offers two different operating modes:
- Hands-free mode for mono intercom functionality
- Stereo playback mode for listening to MP3 content

For the improved playback of stereo music recordings, the device also features 3D audio effects. These use CONEXANT’s proprietary psychoacoustic effects, which give listeners a closer to live listening experience.

Target Applications:
- SmartPhone docking stations with MP3 playback features
- Intercom systems with stereo reproduction requirements
- Full duplex hands-free speakerphones with stereo reproduction requirements

The CX20663 comes in a 48-pin Quad Flat No-Lead (QFN) package.

A brief overview and list of functions for these new SPoC devices, as well as detailed data sheets, can be found at: To find out more about the audio features, please visit: An evaluation kit with a reference board and software is also available.


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SPoC: Speakers on a Chip
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Blockschaltdiagramm CX20562
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Blockschaltdiagramm CX20662
Imp_2_2009_A 02_CONEXANT_Speaker on Chip_CX20663 Blockdiagramm_Bild1_kl.jpg
Blockschaltdiagramm CX20663
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