Electronic Design

ADSL+ Chips Slash Power Consumption With Class D Amps

Class D switching amplifier chips have been around for a while in audio power amplification. Now, Infineon's Geminax Pro ADSL2+ chip set uses class D amplifiers in its line drivers. Because of their very high efficiency, these chips slash power consumption, reduce the chip footprint, and trim overall cost by up to 30%.

Manufacturers of DSLAMs and line cards for DSL can use the set to create new equipment to expand the number of subscriber lines without overwhelming the power and space requirements. In addition to minimizing power, area, and battery backup needs, these chips offer reduced operating costs and heat. Carriers will be able to roll out ADSL2+ systems faster, easier, and cheaper.

By far, DSL dominates high-speed Internet access worldwide, and it is rapidly gaining on cable TV modem access in the U.S. Even greater inroads are promised as the new ADSL2+ standard is implemented. ADSL2+ is an advance version of ADSL that can transmit at a data rate up to 25 Mbits/s. This speed adds video to the Internet and Voice over Internet Protocol broadband mix. But to get those speeds, the circuitry requires more power.

That's why Infineon's class D approach is so desirable in the analog front-end (AFE) line drivers. The Geminax Pro chip set comprises a 16-channel ADSL2+ digital front end (DFE) called the Geminax-D16 Pro and a four-channel AFE with four integrated class D line drivers designated the Geminax-AL4 Pro. Designers need a total of five chips to implement a full 16-channel system.

The chips fit nicely into DSLAMs, digital loop carriers (DLC), and multiservice access platforms (MSAPs). They support full-rate ADSL (G.992.1 ITU standard), ADSL-line (G.992.1), ADSL2 (G.992.3), ADSL2-lite (G.992.4), and the newer ADSL2+ (G.992.5).

A related chip targets integrated voice and data applications from Infineon's Vinetic line of voice codecs and the ConverGate DSL network processor. The company's Amazon family of chips suits customer premise equipment.

The Geminax-D16 Pro comes in a 23- by 23-mm PG-LBGA package, while the Geminax-AL4 is delivered in a 13- by 17-mm PG-BGA package. Samples are now available, with full production planned for the third quarter of 2005. The chip set costs $6.00 per line in sample quantities.

Infineon Technologies AG

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