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The current RF solutions for multimode handsets are inefficient in cost, size and power, and require longer design cycle time. To address these issues in multimode RF transceivers, RF semiconductor supplier Sequoia Communications has combined its polar architecture with 0.18 micron silicon germanium (SiGe) biCMOS process technology to create what it claims is the first true multimode transceiver using a common basic architecture across all modes. According to Sequoia, polar modulation, the standard architecture in GSM, which is being adopted in EDGE, has not been successfully implemented for WCDMA until now. Sequoia Communications' FullSpectra architecture solves this RF design dilemma and delivers the highest impact in WCDMA, where power consumption and complexity are problematic.

According to Sequoia, the SEQ-5400 is the industry's first single-chip, multimode WEDGE (GSM, GPRS, EDGE, WCDMA) RF transceiver. This transceiver will lower the cost and increase the battery life of 3G phones, addressing the primary obstacles in the mass adoption of 3G, said the manufacturer.

The product handles GSM, GPRS, EDGE, WCDMA, HSDPA modes across five frequency bands, making it applicable to all networks worldwide. It achieves the highest level of integration in the market; everything from the baseband interface to the power amplifier, RF synthesizer, receiver and transmit VCOs, and channel filtering is integrated into a single chip, including the WCDMA receive SAW filters (see figure). The SEQ-5400 uses direct-conversion architecture in the receiver to translate the RF signal directly to baseband where channel filtering occurs. This eliminates IF processing and SAW filters. The transmitter architecture uses Sequoia's direct synthesis approach, a form of polar modulation that provides flexibility while reducing power. It employs the FullSpectra polar modulation approach for WCDMA and EDGE modulations.

The SEQ-5400 reduces overall component count and pc-board area more than 50% above other solutions on the market, according to Sequoia. It contains a flexible analog interface to the baseband with a simple upgrade path to DigRF when that standard is ratified for 3G. The transceiver includes the filtering and data converters required by the DigRF standard. The product also interfaces to standard linear power amplifiers.

The SEQ-5400 comes in a 64-pin QFN package. Samples are available. V-olume production is anticipated in the first half of 2006.
Sequoia Communications
(858) 946-7400
www.sequoiacommunications.com

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