The big three "care-abouts" for 3G transceivers are power, size, and cost. With careful engineering and a new approach, the team at Sequoia Communications has managed to attack all three. With the SEQ-5400, Sequoia is the first company to apply polar modulation to WCDMA, and, as a result, the company reports it has the potential to drop power consumption by 50% and boost battery life by 10% over competing architectures.
Polar modulation is the current standard for GSM. In this type of system, the signal is separated into amplitude and frequency, and it is recombined at the end of the signal path. "Right now, we are recombining just before the power amplifier," explains Dave Shepard, Sequoia's President and CEO, "In future generations, we plan to do it at the PA and thus realize even more power savings." Polar modulation is particularly hard to achieve for WCDMA because of its large dynamic range and also because WCDMA and EDGE have non-constant envelopes.
So, how did Sequoia do it? "Our biggest challenge was to get our architecture working on WCDMA, which no one else has done," notes Shepard. "One of the things that makes Sequoia unique is that the engineering team all have a CDMA background. In the end, it came down to patents, invention, very bright team members, and brute force design."
Sequoia is convinced that multimode phones are the future of wireless communications, so they tackled the hardest technology first, and then will be able to address other modes as the market dictates. For instance, future generations of the product are likely to include more bands to target Asian and US markets. And, they have plans to move to a digital interface to enable it to work with more basebands. Other ideas include adding WLAN and OFDM functionality. Currently, the SEQ-5400 transceiver handles WCDMA, HSDPA, EDGE, GPRS, and GSM.
Of course, another key concern for 3G designs is size, and the team at Sequoia worked hard to maximize the integration of their design. Claiming that they have the highest level of integration on the market, a single SEQ-5400 replaces up to six or seven devices, and saves up to 50% of board area and cost as compared to competitive solutions. In addition, a typical BOM includes 140 support components, such as resistors and capacitors, while the Sequoia design includes fewer than 80.
Sequoia was founded in 2000 with the mandate to prove out the concept that polar modulation could be done on WCDMA. By the time the initial engineering work was done, the need for multimode phones were real, and Sequoia has found itself uniquely positioned to serve the market. The chip is sampling to phone makers and reference design providers.
If you are interested in this product, you will be happy to know that Sequoia will provide 4 or 5 reference cards with the SEQ-5400 transceiver, demonstrating how it can work with other manufacturers RF components. The company also offers extensive technical and design support.
The SEQ-5400 is priced at $6.00 to $8.00 each depending on volume. It is sampling now with volume production scheduled for 2006.
+1-(858) 946-7400, www.sequoia-communications.com