The AR3011 from Atheros Communications is the first member of the ROCm Radio-on-Chip for Mobile family of Bluetooth solutions. The device is a Bluetooth 2.1 + Enhanced Data Rate (EDR) solution specifically optimized for PCs, and silicon samples will be available in the first quarter.

The Bluetooth 2.1 + EDR specification delivers an array of connectivity enhancements that focus on providing increased security and power savings, and enhanced usability. Ratification for the standard is expected soon.

In addition to support of this enhanced protocol, the AR3011 features a USB 2.0 device interface, dual 1.2 V voltage regulators, an integrated 32-bit CPU and integrated RAM. Other innovations include VCO fine-frequency control and a hybrid offset/zero-IF architecture.

According to Srinivas Pattamatta, senior product marketing manager, Mobile and Embedded Group for Atheros, PC OEMs to date have had to adapt Bluetooth solutions intended for use in handsets. The AR3011 precludes the effort associated with this practice, while reducing the requirement for external BOM components to six passive devices, a reduction of approximately 60% (see figure).

One difficulty with Bluetooth devices for handsets is the need for external parallel Flash memory, which drives the need for BGA packages and higher-cost modules. Atheros eliminates this requirement by integrating SRAM into the AR3011. The highly integrated design also eliminates the need for a balun transformer and matching network.

Using the hybrid offset/zero-IF architecture, the raw RF receive signals are downconverted and then digitally sampled. This design differs significantly from the design cited in a recent patent infringement lawsuit and has additional benefits such as reducing cost, complexity and noise problems.

However, the switching noise from dc-dc converters that will power the chip is a far more significant source of interference. This issue presented a major design challenge, and it was addressed by leveraging the Atheros’ design team’s working knowledge and experience gained in the development of wireless LAN (WLAN) products. The decoupling of this noise from sensitive circuitry was ultimately accomplished through circuit design techniques and the use of internal and external capacitors.

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