Maxim releases AISG-compliant transceiver

The single-chip solution features a transmitter, receiver and active filters into a 3 x 3mm TQFN package.

The transceiver also provides an auto-direction output to facilitate RS-485 bus arbitration in tower-mounted equipment without requiring a microcontroller.

The high integration of the Max9947 simplifies the implementation of AISG-compliant base stations and tower-mounted equipment.

Third-generation (3G) wireless networks were developed to provide the high-speed data services required by data-intensive smart-phone applications.

However, the deployment of this infrastructure has been costly and coverage has been inadequate in some areas.

Addressing both of these concerns, the Antenna Interface Standards Group (AISG) developed an interface protocol to enable intelligent antenna systems.

The AISG specification allows the digital remote control and monitoring of wireless infrastructure to dynamically optimise the network based on changing coverage requirements.

This open standard has quickly been adopted by telecommunications companies because it frees them from proprietary solutions while protecting their infrastructural investments.

In turn, base-station and antenna manufacturers have benefited from a standardised technology roadmap, which has increased efficiency in product planning.

AISG transceivers can be implemented discretely using any number of components and methods.

They might use active filters or passive filters, different methods for OOK modulation and demodulation, logic for bus arbitration, amplifiers and, in some cases, analogue-to-digital converters.

As each transceiver implementation can use a different architecture to achieve AISG compliance, antenna and base-station original equipment manufacturers must maintain multiple board layouts to accommodate various transceiver designs.

The fact that a transceiver sits in the base station, where there will be a microcontroller or processor, and the tower, which is not likely to have either, further complicates matters.

Any communication between the two sites requires bus arbitration, necessitating a device that can operate under the control of a microcontroller or act independently.

As a result of this requirement, system designers have had to use different transceiver modules for base-station and tower-mounted equipment.

The Max9947 integrates a transmitter, a receiver and active filters to save designers from the hassle and expense of working with discrete solutions.

The device, therefore, reduces the time needed to implement the AISG protocol.

The transmitter includes an OOK modulator, a band-pass filter that is compliant with the AISG spectrum-emission profile and an output amplifier.

The receiver includes a band-pass filter that operates around the 2.176MHz centre frequency with a narrow 200kHz bandwidth; it also includes an OOK demodulator and a comparator for reconstructing the digital signal.

An auto-direction output is provided to facilitate RS-485 bus arbitration in tower-mounted equipment without requiring a microcontroller.