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Envara tips one-chip, multiband WLAN radio

Posted: 10 Jul 2002 ?? ?Print Version ?Bookmark and Share

Keywords:en303? wind502? wlan radio? wireless lan radio? 802.11 radio?

Envara Inc. has announced that it has samples of the RF front end of its much-heralded WiND dual-band, 2.45GHz/5GHz wireless LAN two-chip set.

The EN303 integrates the radio functions for both IEEE 802.11a and 802.11b WLANs and also complies with the current components of the 802.11g draft standard. The direct-conversion radio uses off-chip power amplifiers, but otherwise includes the LNAs, both VCOs, the synthesizer and all filtering.

The Envara announcement comes a week before Broadcom is due to announce a direct-conversion, three-chip, all-CMOS WLAN combo chip set, and two weeks after Synad announced its own entry into what's become a market destined for a shakeout. Others in the arena include Atheros, Intersil, and Systemonic.

"Everyone has dual band on their [WLAN] road map right now," said Paul Nurflus, director of marketing at Envara. "I don't see any future in .11a-only."

Atheros, the leading .11a proponent to date, announced a .11b/g/a combo solution earlier this year. Compliance across multiple bands became a mandate after Microsoft Corp. announced late last year that only dual-band radios would get its WHQL certification.

Implemented in IBM Corp.'s SiGe process, the EN303 has a number of architectural nuances besides the company's enhanced ZIF(EZ-IF) direct-conversion design. The so-called EZ-IF design itself eliminates the dc-offset and adjacent-channel-rejection problems associated with such designs, Envara said, while at the same time giving a 40dB I/Q mismatch figure.

The chip's proprietary, zero-loss front end avoids the use of antenna and diversity switchesand the 3dB loss those switches can incuryet boasts a wide operating-frequency range that allows it to cater to the newly proposed 4.9GHz band in Japan, all the way up to the 5.825GHz band of 802.11a.

The Japanese proposal calls for four RF channels in the 4.9GHz to 5GHz band, with a further three channels in the 5.03GHz to 5.09GHz band. Further "globalization" has been incorporated into the EN303 through the inclusion of dynamic frequency selection, the company said.

In addition, the chip self-calibrates upon power-on, allowing the OFDM modem to digitally modify the OFDM signal to offset the distortion of the RF chip.

The chip is the lead end of the company's planned WiND502 multimode chip set, which will pair the EN303 with an integrated baseband/media-access controller that Nurflus said will sample in September. The full solution will be priced at $30, he said.

The EN303 die measures 20mm2, comes in a 56-pin leadless package and is currently sampling to selected alpha partners. Power consumption is 200mA, not including external power amps.

Patrick Mannion

EE Times





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