Electronic Design

Cheap Chip Makes ULCHs Even More Affordable

What's the fastest growing segment of the cell-phone industry? It isn't multimedia smart phones. In fact, it's the opposite— ultra-low-cost handsets (ULCHs).

Silicon Laboratories says that 71% of all new worldwide subscribers from 2006 to 2010 will be in developing nations, as long as these basic, no-frills phones are cheap enough. Also, the number of potential subscribers will grow from 181 million to 321 million from 2007 to 2009. Silicon Labs hopes to fuel that growth with its AeroFONE Si4901.

This single chip is a complete dualband GSM mobile terminal that can be used in ULCH products. According to Silicon Labs, it's the first and only chip that integrates the power-management unit (PMU), battery interface, and charging circuitry with the digital baseband, analog baseband, and RF transceiver into a single monolithic 0.13-µm CMOS IC. It only needs a power amplifier, a front-end module, and nonvolatile memory to create a complete GSM phone.

The Si4901 is a low-cost chip, yet its higher level of integration decreases the number of external components in the handset. Silicon Labs says it can trim total parts count from about 200 components to 50. This further lowers costs, decreases pc-board space, and improves reliability. Also, the design lets manufacturers abandon the costly six-layer pc board for a less expensive four-layer board.

The Si4901 includes an ARM core, the Ceva-Teak DSP, and the full power-management unit (see the figure). It can be configured for any two bands (850 or 900 MHz and 1800 or 1900 MHz). And, its receiver sensitivity is in the ?113.5-dBm range, ensuring better link connectivity to cell sites in difficult environments.

The Si4901 comes in a lead-free, 10-by 10-mm plastic ball-grid array (PBGA) package that complies with the Restrictions on Hazardous Substances.

Samples are available now. Full production is scheduled for the fourth quarter. An evaluation platform is available for $5000.

Silicon Laboratories Inc.

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