New architecture brings GPS to mobile phones
The SiRF Technology GSCi-5000 self-contained GPS reciever is the RF Design Product of the Month for February 2006.
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To address the space and cost constraints of new and emerging mobile phones, SiRF Technology has combined advances in process technologies with packaging skills and architectural forte to pack an extremely small multimode A-GPS solution into a single miniature ball grid array (BGA) package. Labeled GSCi-5000, it is optimized to deliver a single platform with the benefits of cost, power and size and, thereby, facilitate the adoption of GPS-based applications in cellular handsets and other mobile devices.
In reality, the new GPS platform packs two dies in a 4 × 6 × 1.0 mm-sized, 77-pin BGA package. While the baseband processor in this architecture uses the latest 90 nm CMOS process (see figure), the RF GPS receiver is based on the 0.18-micron silicon germanium (SiGe) process technology to achieve unprecedented size, power and cost metrics, according to Kanwar Chadha, SiRF's founder and vice president of marketing.
In fact, the GSCi-5000 combines many leading-edge features to address the specific needs of modern and emerging mobile phones. To reduce overall system cost and size, the ROM-based GSCi-5000 receiver packs all of the functional blocks of a GPS receiver onto a single die, which includes a low-noise amplifier (LNA) and fractional synthesizer. Thus, it offers high-sensitivity operation with signal tracking to -154 dBm without the need for an external LNA. While the on-chip synthesizer enables the instant GPS to operate from any suitable reference oscillator in the range of 12 MHz to 54 MHz. Plus, its proprietary technology minimizes the impact of RF jamming and compression issues, which can hinder the late stages of the handset development cycle. The GPS-related software is embedded in the on-chip ROM. Overall average power consumption is minimized using a combination of self-managed periodic fix modes and a 5 µA sleep mode.
Using a protocol based on the third-generation partnership project (3GPP) A-GPS messages, the GSCi-5000 is optimized for easy host software integration. Supporting mobile station (MS)-based, MS-assisted, autonomous and multimode operation, the receiver offers the expected levels of flexibility many location-based services will demand. GSCi-5000 A-GPS performance is compliant with the industry-standard 3GPP requirements, with extremely fast assisted fix speeds of <1.5 s in the nominal accuracy test. Copies of the full GSCi-5000 3GPP compliance test report are available on request.
In this package, the baseband processor uses 1.2 V supply and the RF chip operates at 1.8 V. Power consumption is 80 mW in acquisition mode, and 50 mW in tracking mode. It is sampling now to select customers with general sampling to begin in the second quarter, the GSC-5000 is expected to go into production in the third quarter.
SiRF Technology Inc.
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