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Silicon Lab's transceiver streamlines high-volume EDGE designs

Posted: 06 Oct 2005 ?? ?Print Version ?Bookmark and Share

Keywords:enhanced data for gsm evolution? edge? silicon laboratories? gsm? aero?

Enhanced Data for GSM Evolution (EDGE) is getting a lot of attention lately, as manufacturers of GSM handsets look to make the transition to 3G systems and beyond. Many in the industry expect large-scale EDGE production to begin in the next year or so, and, as a result, the design team at Silicon Laboratories has come out with the Aero IIe single-chip EDGE transceiver, which is specifically designed to enable high-volume EDGE handset production. They have eliminated the need for many sensitive external components and have significantly reduced the calibration requirements for EDGE down to an amount that is equivalent to current GSM implementations.

"We have reduced the transceiver calibration requirements down to one step," explained Patrick Morgan, marketing manager for wireless products at Silicon Laboratories. "Competing chipsets in this market have numerous complicated calibration requirements, such as receiver IP2 calibration, transmitter I/Q predistortion, I/Q DC offsets, feedback gain and filtering, PA drive levels, and delay mismatch, which takes time, interrupts the production flow, and, therefore, reduces manufacturing throughput."

So, what is the one step? "Transmitter output power calibration, and it is effectively equivalent to what is used in GSM handsets today," continued Morgan. The transceiver was also designed to hit key performance targets, including transmitter EVM of 4 percent and receiver sensitivity of -110dBm or better.

Keeping mass-production throughputs high requires generous performance margins with no spurious contributions, and the new transceiver offers those for the Output Radio Frequency Spectrum (ORFS) modulation mask. For example, in GMSK the Aero IIe hits -66dBc at 400kHz offset (which is a 6dB margin), and in 8PSK it is -64dBc at 400kHz offset (a 10dB margin). "These performance margins are important, because they enable better production yields," adds Morgan.

The team also focused on integration in order to streamline EDGE handset design. The result is that the Aero IIe is housed in a 5-by-6 mm package and has a BOM with 29 external components for triple-band as compared to competing solutions with up to 65 external components.

The Aero IIe is based on the company's Aero II technology, which is now shipping for mainstream GSM/GPRS handsets. With the new design, the team at Silicon Laboratories focused on integrating the EDGE transmitter circuitry (the receive path is the same as the AeroII). "The main design challenge was to integrate the EDGE circuitry together with the clocking and local oscillator circuitry on chip while taking into account the dangers of interference between the sensitive analog circuitry and the nearby digital circuits," explained Morgan. "Achieving this in mainstream CMOS technology presented a significant design challenge. Fortunately, we had the in-house expertise and processes that allowed us to do it."

Anyone working in GSM and looking to enable high-speed data services would be wise to take a close look at the Aero IIe. You'll be happy to know that it is compatible with all leading vendors for basebands and power amplifiers; it is sampling now, and evaluation boards are available.

- Janine Love


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