Mobile WiMAX has moved from hype to reality, as engineers are increasingly integrating this technology into their next-generation designs. To help them with this task, a number of device manufacturers have developed reference designs. In fact, the first reference design for a MicroTCA broadband wireless transceiver was just announced by fabless startup Lime Microsystems (www.limemicro.com). Targeted at small-cell WiMAX base-station applications-femtocells and picocells-the transceiver has six user-selectable channel bandwidths from 1.5 to 14 MHz. It can be digitally configured to operate in bands from 2 to 4 GHz.

The reconfigurable design supports a variety of network configurations, bandwidths, and data rates. It can be configured for half-duplex and full-duplex operation in both frequency-division-multiplex (FDM) and time-division-multiplex (TDM) modes. The board also can be used as a plug-and-play transceiver for the rapid evaluation and deployment of WiMAX base stations based upon ACTA or MicroTCA standards. The zero-IF transceiver uses 12-b baseband analog-to-digital converters (ADCs) and digital-to-analog converters (DACs). A low-noise clock synchronizes a 40-MHz sampling rate.

The design's serial RapidIO interface supports a throughput of up to 3.125 Gb/s and can communicate via any advanced-mezzanine-card (AMC) ports. A single port carries both I/Q and control traffic. In addition, an I/Q record and playback capability simplifies testing. A full-speed Universal Serial Bus (USB) interface is provided for PC-controlled standalone operation. Lime, which is based in Guildford, UK, says that it has been working closely with a number of companies in both baseband and RF amplifier technologies. Formal partnership announcements are expected in the next few months. It is thought that these agreements will enable Lime to support its customers in the development of complete base stations that guarantee interoperability between the main circuit functions. The development platform will be available from December 1, 2007 at a one-off price of $12,000.