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Wolfson loads audio codec with functionality

Posted: 18 Oct 2004 ?? ?Print Version ?Bookmark and Share

Keywords:wolfson? wm8974? audio codec?

Traditionally, Wolfson developed platform-type products that support a broad range of portable and non-portable consumer audio applications. Today, Wolfson has decided to zero in on specific portable applications when they can identify a market of sufficient size with specific requirements in terms of a feature set and performance.

Wolfson's latest devicethe WM8974, is a mono audio codec designed for digital still cameras (DSCs) and digital-voice recording applications, such as dictaphones.

The DSC market, which is growing 30 to 40 percent annually, is expected to reach approximately 80 million units worldwide this year, according to market analysts.

"Now that the DSC market has evolved to the point that it has, Wolfson has seized the opportunity to produce a codec specifically designed for this application, with a lot of functionality, as opposed to using a common platform product," said John Crawford, product marketing engineer for portable products.

The highly integrated WM8974 codec offers many technology improvements over its previous-generation codecs, Crawford added. The new codecs, for instance, are being offered in a 4-by-4mm QFP, compared to the 5-by-5mm QFP, he said.

Utilizing a new DSP core enabled the company to reduce the die size and develop an enhanced feature set. This also contributed to reduced power consumption. The system requirements for the DSC market also allowed a slightly reduced number of I/Os, which helped support a smaller package, Crawford explained.

Additionally, the company has achieved a 10 to 20 percent performance improvement on the digital-to-analog converter (DAC) side with signal-to-noise ratio (SNR) in the current product offering 98dB playback, compared to its previous generation products, which offered dBs of around 89 to 90. "This technology improvement enables the camera to capture a wider scope of sound that is clearer," Crawford commented.

The new DSP core provides high sound quality benefits such as noise reduction. The wind noise filter feature, for example, reduces the sound of wind when recording outside on a windy day. In addition, the programmable notch filter reduces motor noise by preventing the camera from picking up the motor noise caused by the lens moving in and out when using the zoom capability. And, despite its tiny size, Crawford stressed, the chip includes a five-band graphic equalizer to play back small video music clips.

Despite drawing low power, the WM8974 codec can still drive really load speakers. Speaker output power has increased to 900mW, compared to 500mW in the previous generation products.

Integrating the core function to include all of these special audio features will save design engineers from having to integrate these features onto the codec themselves, Crawford said. The new device is the first in a suite of codec products that will follow from Wolfson. The company plans to next target the smartphone, PDA and DVD player markets.

- Bettyann Liotta


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