Electronic Design

DSL Chip Set Boosts User Benefits, Performance

Aimed at central offices and tuned for the latest DSL standards, this chip set enhances the user experience for both businesses and consumers.

As central offices (COs) try to generate better DSL services for consumer and business users, they need to upgrade their DSL line cards to incorporate the latest signalling standard and advances in signal-processing technology.

Centillium Communications has addressed all of these details and added enhancements that extend the distance delivered by DSL lines. Higher-performance DSL lines are needed as e-mail and other Internet applications include more audio and video attachments or users want to view or listen to media files directly from the remote server. The faster connections will help enhance the users' experience by allowing the streaming files to be sent with minimal delays.

The Maximus chip set lets designers deliver such capabilities—high bit rates and an expanded coverage area (up to 22,000 feet from the CO). Its digital chip packs 12 full-rate ADSL data pumps, an extended Utopia level 2 interface, and a 16-bit parallel host-bus interface. Its analog front-end chip includes programmable gain control for the transmit and receive paths, along with high-speed/high-resolution analog-to-digital and digital-to-analog converters.

On-chip circuitry provides an intelligent selection capability that allows the interface to select between ADSL, ADSL2+, and quad-spectrum ADSL modes. Centillium incorporates its eXtremeDSL technology to help extend reach by optimizing the ADSL spectrum, significantly improving the downstream and upstream bit rates. At the same time, the chips maintain backward compatibility with ADSL, ADSL2, and ADSL2+ standards.

The eXtremeDSLMax features provide a quad-spectrum downstream capability of up to 50 Mbits/s or a double-spectrum downstream speed of 24 Mbits/s. Extending the DSL lines' reach to 22,000 ft (7 km), the technology greatly increases the number of possible users that can connect through a single CO. Upstream data rates of up to 3 Mbits/s are also possible. Some of this performance is achieved by using higher bit loading on each discrete-multitone (DMT) subcarrier (a loading of more than 15 bits per DMT subcarrier).

By slashing the bill-of-materials cost and space required for a 12-port line card, the CT-L76DC12 Maximus chip set can bring the cost per port of DSL subsystems to well below $10 per port. The digital chip comes in a 420-contact BGA package. The analog front end comes in a 326-pin BGA package. Samples are immediately available.

Centillium Communications

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