Electronic Design

EDR Standard Infuses Speed, Lowers Power In Bluetooth Chips

Some thought Bluetooth would never arrive, much less be successful. But the industry has quietly plugged away over the past couple of years and made it a big success. Already, 150 million more Bluetooth chips have been shipped this year than in all of 2003--not too bad. Bluetooth's main use is in cell-phone headsets, yet many PC peripherals take advantage of Bluetooth as well. It's also showing up in wireless MP3 players and game pads.

Now, Bluetooth is poised for additional applications and growth with the new Bluetooth SIG standard. Enhanced Data Rate (EDR) Bluetooth provides three times the data rate of the current v1.2 standard. It offers a maximum user rate of 2.1 Mbits/s, up from the previous high of 721 kbits/s. This increase opens the standard to even newer applications like high-quality wireless surroundsound systems. It also consumes less power because the data is transmitted faster with shorter and fewer packets, minimizing transmitter on-time.

Cambridge Silicon Radio is one of the first companies to implement the standard, using it in its BlueCore4 chips. The chips provide full EDR features while remaining backward-compatible with v1.1 and v1.2. The EDR version uses differential quadrature phase-shift keying (DQPSK) modulation instead of the usual gaussian frequency-shift keying (GFSK) in the older standards. The symbol rate remains at 1 Mbit/s, but the greater number of bits per symbol provides the higher data rate.

The BlueCore4 chips come in two forms. BlueCore4-External uses external flash memory, while BlueCore4-ROM relies on a mask-ROM. The latter chip is fully pin-compatible with the older BlueCore2 and BlueCore3 designs, making product updates faster, easier, and less expensive.

The devices come in an 8- by 8-mm, 96-pin VFBGA package. Each has USB and UART I/O. BlueCore4 is also compatible with Wi-Fi chips. It permits full coexistence thanks to adaptive frequency hopping that maps and avoids 2.4-GHz channels used by nearby 802.11b/g transceivers.

Samples are available now, with production of the External version coming in November. The ROM version is slated for February 2005. Contact the company for pricing information.

Cambridge Silicon Radio
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