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Transceivers enable thumb-sized WiMAX terminals

Posted: 27 Sep 2007 ?? ?Print Version ?Bookmark and Share

Keywords:WiMAX? baseband transceivers? thumb-sized terminals?

 AD9354, AD9355

Analog Devices Inc. has introduced RF-to-digital baseband transceivers designed to enable broadband connectivity in mobile communications terminals, such as cellphones, PDAs and handheld multimedia devices using WiMAX.

As WiMAX evolves from a fixed-line protocol to one that increasingly serves portable communications applications, device manufacturers are requiring smaller, more energy-efficient solutions that deliver IEEE 802.16d/e mobile WiMAX standard compatibility within the cost, space and power budgets of mobile communications terminals.

Building on ADI's AD9352 and AD9353 integrated WiMAX transceiver components introduced in 2006, the AD9354 and AD9355 components consume less power than other transceivers in their class and are available in a package that is 20 percent smaller, while adding an additional receiver path for multiple-input, multiple-output (MIMO) support. The power and space savings of the AD9354 and AD9355 components enable manufacturers to incorporate WiMAX functionality into handsets, thumb drives or PCMCIA cards.

By integrating ADCs, DACs and real-time control and calibration loops, the transceiver components repartition the signal chain, combining all analog and RF functionality on the AD9354 or AD9355 components. This frees providers of the communications and applications processors to manufacture their digital products in the most cost-effective digital CMOS process technologies, reducing power, package size and system design complexity.

The AD9354 and AD9355 transceivers integrate two direct-conversion receivers that provide support for MIMO technology, which ensures that mobile devices achieve uninterrupted WiMAX service. The direct-conversion transmitter architecture achieves error vector magnitude (EVM), maximizing network throughput. The transceivers communicate with a WiMAX terminal's baseband ASIC or FPGA using the industry standard JESD207 digital interface that ADI help to define. The data bus requires 13 pins, which is comparable to competitive products employing analog interfaces.

"By including on-chip data conversion and adding a second receiver signal chain to our transceiver architecture, ADI is helping communications service providers extend WiMAX into the mobile marketplace," said Thomas Gratzek, business director, WiMAX transceiver group, ADI. "The AD9354 and AD9355 cover the key WiMAX frequency bands and are ideally suited for the small form factors in development."

The AD9354 and AD9355 operate in the 2.3-2.7GHz and the 3.3-3.7GHz ranges and support channel bandwidths of 3.5, 4.375, 5, 7, 8.75 and 10MHz. The devices have an excellent 3.25dB noise figure and best-in-class linearity, both enabling optimum real-world performance as WiMAX network traffic increases, said ADI. The smart partitioning architecture enables autonomous automatic-gain control, transmit-power control and calibration routines that dramatically reduce the RF driver development effort. Moreover, the highly accurate closed-loop power control enables one-point factory calibration of transmit power. In contrast, other transceivers require 8 to 10 calibration points, which increase final test costs and extended development times.

The AD9354 and AD9355 mobile WiMAX transceivers are sampling now. The devices are priced at $11.45 per unit in sample volumes. The AD9354 and AD9355 are housed in an 8mm x 8mm, 64-lead LFCSP (lead-frame chip-scale package).

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