Silicon Labs has unveiled a single chip that enables the construction of a 58-component GSM/GPRS mobile phone. It is aimed at very low-cost handsets for developing countries.

The all-CMOS AeroFONE Si4905 includes the power management unit (PMU); battery interface; charging circuitry; digital and analogue basebands; and a quad-band RF transceiver.

It uses Silicon Labs' Aero II transceiver, which employs second generation DCXO technology instead of a CC-TCXO. There is 2Mbit of on-chip SRAM, so a GSM voice-only implementation can be built without external memory. The PA, two crystals, SAW filters and antenna switch module are off chip.

Phone implementations using previously announced single-chip designs – for example Infineon’s PMB7870 E-GOLDradio, which was announced in July and reduces the number of components to “less than 100” – require a separate chip for the power management unit, said Silicon Labs.

Interest in ultra-low cost mobile handset development has emerged following the recognition that cellular could be the first telecoms installation in many developing countries.

A tender announced last year by the GSM Association for a sub-$40 handset to satisfy that market was won by Motorola.

That design featured 245 components, and Silicon Labs said getting that down to 58 significantly reduces manufacturing cost and improves yield.

James Kimery, marketing director for wireless products at Silicon Labs, said that designing for low-cost markets also entailed improving performance, to reduce the amount of infrastructure required.

“It may be surprising, but designing for low cost also means designing for high sensitivity,” he said. “Because it means operators can install less dense networks in developing regions.”

To that end, Silicon Labs claimed an informal benchmark against a Motorola C115 phone showed the Si4905 offered 2dB better sensitivity on average across the 900MHz band.

The Si4905 uses an ARM9 core and a Ceva Teak DSP, on a 0.13µm process. It is packaged in a 12x12mm BGA, and mass production is scheduled for Q2 next year.

www.silabs.com