Electronic Design

Software-Configurable Codec Provides Low-Cost Audio Quality

To boost sound quality at lower cost in PCs and notebooks, Analog Devices has combined the popular AC'97-compliant codec with DSP technology on a single 0.35-µm CMOS chip. As a result, the AD1981 now provides a powerful codec with software-configurable parametric speaker equalization (EQ) in a single 48-pin TQFP package.

The digital filter circuitry built into the AD1981 lets motherboard designers adjust the center frequencies and bandwidth. This brings flexibility in tuning audio subsystems for specific speakers or audio conditions. The codec itself is supported by device driver and configuration software, which simplifies the design and configuration of response parameters in audio applications. In essence, this intuitive graphical programming tool allows designers to set center frequency, bandwidth, and in-band attenuation to meet system specifications.

"No other audio codec provides the combination of digital audio processing and legacy compatibility for consumer and commercial PCs with such an attractive cost structure," says John Croteau, product line director for ADI's Computer Products and Services Group. By digitally compensating for acoustic limitation, he adds, it can make even inexpensive speakers de-liver premium sound.

The audio codec's integrated phase-locked loop (PLL), power regulator, microphone pre-amplifier, and EQ circuitry cut external component count to substantially lower system cost. The AD1981 also provides 70 16-bit words of coefficient memory for storing filter coefficients. And, it features an S/PDIF interface for connection to digital speakers.

Sampling now, the AD1981 is slated for production in the first quarter of 2002. In OEM quantities, it costs $1.80.

Analog Devices, Integrated Audio Group, Three Technology Way, Norwood, MA 02062-9106; (800) 262-5643; www.analog.com.

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