Tiny Wi-Fi chip debuts
By Maury Wright -- EDN, September 18, 2003
Now that 802.11 or Wi-Fi wireless LANs have pervaded the notebook PC, the attention of the IC vendors turns to other potential Wi-Fi hosts. Many PDA users add Wi-Fi capability via CompactFlash 802.11 cards, and such connectivity is valuable at conventions. Consumers may also demand Wi-Fi in cell phones, MP3 players, digital cameras, and other tethered appliances. In the case of digital cameras, for instance, Wi-Fi would allow transfer of photos from a camera to a PC on the wireless network at much higher speeds than Bluetooth would allow.
However, to effectively address small portable devices, such as PDAs and cell phones, system designers need physically more compact Wi-Fi implementations than those that notebook PCs use. Early notebook users added Wi-Fi via PC Cards. Now, many notebooks embed the Wi-Fi capability. Generally, system designers buy Wi-Fi modules in the mini PCI form factor rather than mounting the capability on the main-system pc board. The module approach allows system designers to avoid the complex analog design of the RF products. Moreover, regulatory agencies can certify the modules separately from the notebook PC, removing that hurdle for PC vendors.
Mini PCI modules measuring 50×60 mm, however, are still too large for PDAs and other small devices. Wi-Fi implementations require much of the Mini PCI real estate, so vendors can’t just use a smaller module, and discrete analog components occupy much of the module’s area.
Broadcom claims to be the first company in line with a smaller module design for 11-Mbps 802.11b networks. The company’s new AirForce OneChip addresses the size issue in two ways. First, the chip integrates both the digital baseband and the analog radio. Broadcom had previously shipped the radio chip using a CMOS digital process employing the company’s Direct Conversion RF technology. Now, Broadcom includes the Direct Conversion function, the baseband, and many of the discrete components in the IC. A Wi-Fi module that uses the new chip requires only 30 discrete parts, whereas the company’s two-chip module required 200 such parts. This approach decreases the bill of materials for the discrete components by $5.
Assuming that Broadcom can deliver the OneChip, and it claims to be shipping module reference designs to close partners, the new IC will enable 14.8×26.5-mm modules. The design is small enough to go into SD Cards, PDAs, and cell phones. Moreover, the new design delivers better sensitivity for improved performance, along with huge power savings: Standby power decreases from 600 to 6 mW. The device costs approximately $10 cost in high volumes and will cost less in implementations lower than Mini PCs. A few notebook-PC vendors may integrate the new module, although the PC industry is largely moving to faster 802.11g and 802.11a technologies. Broadcom claims that it will later implement a single-chip 802.11g variation. Meanwhile, it has also packaged both 802.11g and Bluetooth in the same 14.8×26-mm footprint and will sell that module for around $14 in volume.
Broadcom Corp, 1-949-450-8700, www.broadcom.com.
