Most of the ICs we cover in Electronic Design are new products that really have something to offer. With hundreds of new chips announced annually, it’s a challenge to identify those that push the speed, power, and size boundaries or have unique features. We look for innovation. You wouldn’t think, then, that the Wi-Fi radio chips I selected as the Best Communications/ Wireless products would be, well, the winners. Yet these new chips do offer something better.
NEW PORTABLE APPS
Wi-Fi has turned into a stellar wireless technology and standard (IEEE 802.11). It’s widely used in enterprise local-area networks (LANs), hot spots, and home networks. But up until now, it has found homes primarily in fixed and mobile device applications like laptops and even some cell phones—applications with significant power available.
Breaking new ground, G2 Microsystems introduced a low-power systemon- a-chip (SoC) and related module that allows Wi-Fi to be used in a wider range of applications that work from smaller batteries, like remote controls and asset tracking tags.
The G2C547 is a fully 802.11b/gcompatible radio media access controller (MAC) and physical layer (PHY) on a chip that also comes with its own 32-bit CPU (a version of SPARC), memory, and some very interesting I/O (Fig. 1). Memory consists of 128-kbyte RAM and 512-kbyte ROM. A 2-kbyte battery- backup ROM is also provided.
The I/O is for external flash, UART, GPIO, SDIO, and SPI (both master and slave). An interesting addition— not typically part of a Wi-Fi chip—is a collection of sensor interface circuits, including analog-to-digital converters (ADCs) for temperature, motion, security seals, and other functions.
For this type of low-power IC, the onchip regulators and power-management circuits are a given. Thus, many applications won’t need an additional processor. Yet the chip will work with an external 8- or 16-bit controller as required.
Full crypto hardware covers AES-128, RC4, MD5, SHA-1, and CRC-32. The complete 802.11i security features are implemented for WEP and all versions of WPA. In addition, the eCos operating system (OS) running on the processor includes the complete TCP/IP stack and drivers, making Internet connectivity easy to implement. A real-time clock makes for wakeup and time-stamp functions as well as a super-fast boot.
The G2C547 also comes with features that make it useful in a wide range of asset tracking and other tagging applications. The device includes a complete 125-kHz transceiver that’s typically used in various RFID applications. Furthermore, the G2C547 supports the EPC Gen 2 900-MHz RFID standard. It contains circuitry to implement realtime location systems (RTLS).
Its ISO 24730-2 time distance of arrival (TDOA) location technology lets you use the chip in tracking and location schemes for major assets, like keeping track of equipment in a hospital. These applications can use the existing Wi-Fi access points to implement an enormous range of location services. Equipped with in-place infrastructure plus this chip, you can assemble a flexible tracking system at a very reasonable cost and time of implementation.
The device, which comes in a 10- by 10-mm, 72-pin quad flat no-lead (QFN) package, works from -40°C to 85°C. Typical power-consumption figures are 10 µW in sleep/standby mode, 79 µW in listen mode, and 117 µW in active orthogonal frequency-division multiplexing (OFDM) receive mode.
If you aren’t a wireless whiz, you can also get the G2M5477 module. It uses the G2C547 chip plus a +20-dBm power amp and antenna, crystal, and other discretes to create a final working product. The module is already FCC and CE certified and tested for Wi-Fi Alliance apps like Wireless MultiMedia. Just drop it right into your product and go.
The G2C547 is sampling now. Initial pricing is $9 in 100,000-unit quantities. A development evaluation board, software, and other accessories are also available. The G2M5477 module costs $22 in 10,000-unit lots. High-volume production is planned for February 2009.
GUARANTEED BANDWIDTH
At least a half-dozen companies make transceivers for the 802.11n Wi-Fi standard. All comply with the Draft 2.0 standard and the Wi-Fi Alliance’s interoperability guidelines so they can deliver at least 100 Mbits/s within the typical unobstructed 100-m range. They also interoperate but lack any significant distinction from one another. Yet Quantenna Communications’ QHS Wi-Fi chips change that tune with significant features and improvement over the more common chips.
When dealing with limited multipleinput multiple-output (MIMO) of the 2-by-2 or 2-by-3 variety, link distances and throughput rates are typically unpredictable. Thanks to an unending number of environmental conditions, you can only guess your connection range and speed.
Limited range means that coverage in a home or with an enterprise access point will have dead zones, ultimately translating into connection unreliability. In critical applications like video, that can greatly limit the usefulness of wireless. In fact, few vendors will support video over Wi-Fi.
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