Manhasset, N.Y. SiGe Semiconductor is leveraging its RF experience and moving farther up the signal chain by sampling a WiMax transceiver.
In doing so it enters a market still fraught with uncertainty and risk in the face of competing wireline and cellular technologies but continuing to gather momentum with a strong backing of silicon suppliers.
WiMax is essentially an interoperability specification that builds on the IEEE 802.16d-2004 standard. It has an Internet Protocol (IP)-based routing structure and nonline-of-sight (NLOS) capability derived primarily from its orthogonal frequency division multiplexing (OFDM). While initial target markets range from last-mile access and cellular back haul, another version based on a soon-to-be-ratified standard called 802.16e, promises full mobility with high-speed access.
Though WiMax faces competition from cable and DSL on the last-mile-access side, proponents expect rural areas and T1 replacement to be key markets. On the mobile side, the debate continues over whether WiMax can compete against next-generation cellular systems in the form of high-speed downlink (or uplink) packet access (HSDPA). "We're 50/50 on that," said Andrew Parolin, director of wireless data products at SiGe Semiconductor (Ottawa), expressing the uncertainty in the industry at large over the outcome of the upcoming turf war.
That said, Parolin is very bullish on WiMax in general, particularly for voice over IP and data applications, he said. In addition, WiMax gives the company an opportunity to move up the signal chain to encompass the full transceiver, from the switch back into the intermediate-frequency stage. To date, the company has been more limited to the front end in its development of Bluetooth, wireless LAN, GPS and cellular ICs. For these applications it would partner on reference designs in which it would complement other company's CMOS-based ICs and agree to noncompete clauses with those partner companies. The company, for example, would provide only the power amplifier for cellular applications, Parolin said. "WiMax offers us an entry point," he said, "to higher-margin, higher-value offerings."
To that end, the company is introducing four chips that will see it cover the signal chain up to just before the WiMax baseband for both the 2.5- and 3.5-GHz bands. Nothing will be done by SiGe for the 5-GHz band for another 9 months, said Parolin. With the announcement, the company is joining a host of well-known semiconductor suppliers, including Intel, Fujitsu, Wavesat, Sequans, TeleCis, Atmel, RFMagic and Sierra Monolithic. However, of those, only the latter three are going after SiGe's target market of the RF front end.
Working back from the antenna, the new ICs are the SE7380L 3.5-GHz GaAs PHEMT single pole double throw (SPDT) switch, the SE7351L and SE7251L 3.5- and 2.5-GHz RF HBT transceivers, respectively, and the SE7051 intermediate frequency (IF) SiGe-based transceiver. Missing are a power amplifier (PA) and the 2.5-GHz switch. "The PA is in development and we expect that by the second half of '05," Parolin said. "The 2.5-GHz switch should be done by Q4 if at all," he said, emphasizing that the 3.5-GHz band is the sweet spot for WiMax right now.
The SE7351L and SE7251L support tuning ranges from 3.3 to 3.8 GHz and 2.3 to 2.7 GHz, respectively, and deliver 40 dB of gain control. Aside from lowering the overall bill of materials for WiMax, the chip sets' IF transceiver has the flexibility of both I/Q and IF interfaces in one chip, "so it can interface to any baseband chip out there," Parolin said.
The device provides dual IF and RF synthesizers as well as a high-speed digital variable gain amplifier with 50 dB of gain control.
Other features on the receive side include a third-order intercept point of 5 dBm, a noise floor of under 6 dB (including switch and filter losses) and an overall maximum gain of 100 dB. The phase noise is under 0.8° rms.
The SE7351L and SE7251L are each packaged in a 40-lead QFN package measuring 6 mm2. The SE7051L is packaged in a 56-lead QFN package measuring 8 mm2 and the SE7380L is packaged in a 6-pin QFN. Sampling now, the chip set will be priced at $30 in volume quantities. Production quantity for the RF stage is set for mid-May and for the IF stage it's set for the end of June.