Electronic Design

Bluetooth, Low-Power Bluetooth, GPS, And FM Radios Fit On One Chip

Cambridge Silicon Radio has sold more than 1 billion Bluetooth chips, and that number is only going to get bigger. Now, the company’s BlueCore 7 represents a breakthrough in wireless integration, as its four separate radios provide increased functionality for cell phones without requiring extra space or power consumption (see the figure).

The BlueCore 7 includes Bluetooth version 2.1 + EDR with its 3-Mbit/s data rate. Instead of older 130-nm technology, it uses 90-nm technology to boost its receiver sensitivity to +90 dBm and its transmit power to +10 dBm. Its ultra-low-power (ULP) Bluetooth transceiver (formerly WiBree) can communicate with watches, medical sensors, remote controls, and other low-power devices. This low power consumption comes from its scan cycle, which is shorter than standard Bluetooth (3 versus 32), and its lower transmit power.

CSR also added a GPS receiver to the chip, since more handsets now incorporate GPS for navigation, location, and E911 compliance. Most GPS receivers on a separate chip take up more space and consume more power. But using the resources that already are available on the chip greatly reduces the required amount of circuitry as well as the power consumption. Furthermore, enhanced features developed by a group of manufacturers enable the chip to identify its location when a full view of GPS satellites isn’t available by using cell-tower triangulation, much like Assisted GPS systems.

The fourth radio, an FM receiver and transmitter, covers the standard 88- to 108-MHz band. The receiver provides –110-dBm sensitivity and incorporates the standard Radio Data Service (RDS) feature that many stations use. With its 4.5-dBm power output, the FM transmitter can send information such as MP3 music from the cell phone to a car’s FM radio. The FM circuits can use shorter antennas than those usually required for adequate reception and transmission as well.

Finally, the optional AuriStream voice codec uses adaptive differential pulse-code modulation (ADPCM) and significantly increases audio quality with its wideband (8 kHz) speech processing. It also consumes less power than the standard Bluetooth continuously variable slope delta (CVSD) codec.

With the BlueCore 7, handset designers can really cram more features than ever before into an increasingly smaller unit. And, it does so without consuming more overall power. Its 3.2- by 3.6-mm package and eight external components make it an easy choice. Full production is expected later in the year.

Cambridge Silicon Radio


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