Electronic Design

Baseband Chips Move 3G Cell Phones To The Fast Track

Are we there yet? That is, to 3G? Well, almost. It's been a long trip with many stops for economic, business, social, and regulatory issues. Yet Agere Systems' combo UMTS/EDGE chip set will give multimode phones the kick they need to get back on the road.

3G cell phones promise packet speeds from 384 kbytes/s to 2 Mbytes/s. That's enough for e-mail, Web browsing, messaging, music downloads, and some video. But to get there, entire cell-phone systems need to be refitted with new hardware and software, according to the ITU's 2000 definition of the Universal Mobile Telephone System (UMTS). Also, these phones will have to support existing legacy technologies.

That's why carriers have opted for a more conservative route with 2.5G phones like the GSM/GPRS and the CDMA2000 1x. Now, carriers are upgrading to 3G with EDGE on GSM/GPRS phones and EV-DO on Qualcomm CDMA2000 1x phones.

Most carriers will eventually migrate to the wideband CDMA (WCDMA) UMTS standard as costs and conditions permit. In fact, it's already happening in Europe. A mass-market multimode phone with some backwards compatibility will push the movement forward as 3G gradually rolls out.

Agere's Sceptre HPU W-EDGE three-chip set combines a GSM/GPRS/EDGE-compatible phone with a real WCDMA UMTS cell phone. This baseband set delivers 384-kbit/s download speeds in 3G/WCDMA mode and 220 kbits/s in 2.5G/EDGE mode, with seamless switchover between systems. Core features include full-duplex speakerphone, MP3 and AAC audio playback, MPEG-4 playback and record, and an SD/MMC memory-card interface.

The analog baseband chip (ABB) contains the analog-to-digital and digital-to-analog converters and other interface circuits to and from the RF chip (see the figure). It also manages power for low consumption and long standby and talk times. The digital baseband chip (DBB) handles all of the voice coding and decoding as well as the system management functions. Its ARM-946ES and dual DSPs tackle the baseband chores. A separate UMTS baseband chip handles all real 3G operations with its separate RF chip.

The EDGE and UMTS stacks were fully tested on real carrier systems, ensuring full interoperability. This chip set works with existing multiband RF radio chips from Silicon Laboratories, RF Micro Devices, and other companies.

The HPU supports the 800-, 850-, 1800-, and 2100-MHz bands. It fully complies with 3GPP release 99, which is the global standard for 3G/UMTS solutions. Agere also offers a full software development suite and reference designs to speed time-to-market with the desired special functions.

The chip set is currently sampling to key customers. Full production is expected by the third quarter of 2005. Pricing is based on quantity, so contact the company for more information.

Agere Systems

TAGS: Digital ICs
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