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CMOS transceiver targets HSPA, WCDMA and EDGE

Posted: 30 Jan 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Janine Love?

SW3200 RF transceiver

Sure, transceivers for 3G handsets have to be small, have low power, and good performance, but they also have to be manufacturable in high volumes with high yield. That's what the team at Sirific Wireless had in mind when they committed themselves to develop a single-chip HSDPA/WCDMA + EDGE (WEDGE) RF transceiverand do it in CMOS.

"If you look at transceivers today, they all have different requirements for manufacturability," observes Kiran Konanur, VP of sales and marketing at Sirific Wireless. "There is a great deal of talk about polar loop architectures, but they require a significant amount of testing in the manufacturing test line to get the handset qualified. Instead, we have implemented a low-noise, wide-band direct up-/down-conversion architecture that is very simple to calibrate on the transmit side."

The team agrees that their greatest design challenge with this chip was implementing it in CMOS. "It takes a great deal more design time to work in CMOS and meet cellular standards," explained Konanur, "That's why most transceivers are in BiCMOS." Sirific Wireless works with TSMC and has implemented the SW3200 in 0.13?m CMOS.

In terms of size, the design team at Sirific Wireless responded to the increased functionality in 3G phones by bringing as much functionality on chip as possible and paring the device size down to 7-by-7-by-1mm. The SW3200 integrates a quad-band GSM/EDGE transceiver, a multi-band HSDPA/WCDMA transceiver, an on-chip sigma-delta fractional-N synthesizer design that requires no external loop filter components, and an on-chip 26MHz digitally controlled crystal oscillator (DCXO). When it comes to power, the device draws 115mA of current (Receiver + Transmitter) in WCDMA mode, which the company reports is a more than 15-percent improvement over the competition.

The end design does not skimp on performance either; here are some key technical parameters:
? Using the SW3200, a handset manufacturer can achieve a GSM receive sensitivity of -113dBm at the LNA input.
? The SW3200 includes a WCDMA receiver with an EVM of 8 percent, which enables HSDPA (CAT 9) downlink data rates of up to 10.2Mbps.
? The SW3200's WCDMA transmitter exhibits an EVM of less than 4percent over the entire output power range.

So, how did they do all this? The team at Sirific has been very busy developing new techniques and intellectual property (IP). Even though this is its first product, the young company already boasts 7 patents and 64 pending. "IP allows us to achieve very low noise output in our GSM/GPRS transmitter, and removed the requirements for transmit SAW filters," said Konanur. The company also has IP in the receiver to achieve the EVM for HSDPA data rates and IP in the synthesizer which removed the requirements for any external components on the loop filter.

For designers of next-generation handsets, the SW3200 is surely worth a closer look. It is a "real" device and is sampling now. Pricing begins at $7.95 in 10,000-unit quantities.

- Janine Love
eeProductCenter




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