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Broadcom, Marvell show CMOS 802.11b chipsets

Posted: 28 Jan 2002 ?? ?Print Version ?Bookmark and Share

Keywords:broadcom? marvel? cmos chipset? networking chipset? ieee 802.11b?

Broadcom Corp. and Marvell Semiconductor Inc. have each announced two-piece CMOS chipsets that support the IEEE 802.11b specification for WLANs, though they are following separate strategies to take a bite of the market currently dominated by Intersil Corp. and others.

Broadcom's focus is as much on integration as on security. The company has married its BCM430x baseband/MAC processors with its BCM2051 single-chip direct-conversion radio. The SiGe power amplifier required for the design remains off-chip. For Marvell, the focus is on integration and low power. Its 88W8000 fully integrated CMOS RF front-end has been paired with the 88W8200, a baseband processor with a DSP engine that allows optimal-channel selection.

Both pairs are aimed at a WLAN chipset market that Cahners In-Stat Group forecasts will grow from $319 million in 2001 to over $1 billion by 2004. Allied Business Intelligence Inc. said that 802.11b solutions accounted for $246 million of last year's $298 million market for WLAN ICs. The total market for WLAN silicon is projected to grow to $1.1 billion by 2006, Allied Business Intelligence said.

However, "We see a crises of leadership [in the WLAN market] in terms of security and single-chip integration," said Jeff Abramowitz, who left Intersil only weeks ago to become senior marketing director at Broadcom. "That's where we see the holes, and that's where our single-chip baseband/MAC and accompanying direct-conversion radio are targeted."

The integration of Broadcom's direct-conversion design eliminates the external SAW filter, VCO and other components needed by a typical superheterodyne radio design. But it does so without any of the typical compromises in terms of sensitivity, interference rejection and IIP3 points, Broadcom said. "We have a sensitivity of -92dB at the lower data rates, and -84dB at 11Mbps," Abramowitz said.

The use of direct conversion puts the Broadcom solution squarely in the path of Intersil's SiGe BiCMOS-based Prism 3 chipset, which has a sensitivity of -85dB at 11Mbps. Announced late last year, the Prism 3 is set to ship this quarter with a bill of materials of under $30. That will make it "15 to 20 percent under Intersil's [original] $35 price point," Abramowitz said. "The Prism 3 also comprises a radio, a baseband/MAC and a separate PA [power amplifier].

Half the battle

But supplying chipsets is only half the battle, according to Larry Ciaccia, vice president and general manager of the Wireless Networking business at Intersil. "There's a lot more to do in terms of Wi-Fi compliance testing, drivers, firmware, features, and Windows hardware certification," he said. The Broadcom solution verifies Intersil's market, Ciaccia said. Intersil has shipped 8 million .11b chipsets to date, he said.

Broadcom's MAC solutions have a number of noteworthy options, said Navin Sabharwal, director of residential and networking technologies at Allied Business Intelligence. Specifically, the BCM4302 adds simultaneous v.92 modem functionality, the BCM4304 adds simultaneous 10/100 Ethernet functionality, while the BCM4307 adds both v.92 modem and 10/100 Ethernet functionality. "These designs will save costs for OEMs embedding WLAN functionality into devices like notebooks," said Sabharwal. "However, Intersil also has this on its road map."

Abramowitz said the chipset's MAC advantages lie in its range of security options. Along with the basic 40-bit encryption of the IEEE 802.11 wired equivalent privacy (WEP) standard, the MAC family includes hardware support of the 128-bit extension of WEP, 802.1x, Temporal Key Initiation Protocol (TKIP) as well as the Advanced Encryption Standard (AES) protocol planned for the forthcoming IEEE 802.11 TGi security specification.

Intersil's Ciaccia said he was not impressed with those features. "Everyone has 802.1x implemented today, and we can add firmware to do AES as the 802.11i task group finalizes the standard," he said. But he acknowledged the speed advantages of a hardware implementation, especially for AES encryption processing.

The Marvell chipset doesn't integrate a MAC, and works with Atmel Corp.'s MAC for now. "Our focus is plainly on integration and power consumption," said Marvell's Bill Windsor. Data sheets put the transmit power consumption at 200mW with no external PA. Though a 20dBm radio is integrated on board, Windsor said this won't get to 11Mbps at 100m. "So an external PA will be required for those rates and distances," he said.

"The chipset, as is, targets low-cost short-distance applications, such as the home or small office," said Windsor. Pricing was not finalized at press time. "We have plans to integrate the MAC on board [with the baseband chip]," he said, though a time frame for doing so was not available. The chipset is sampling now, with production time lines to be determined.

Patrick Mannion

EE Times

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