BRUSSELS — Lime Microsystems, a fabless semiconductor company specialising in digitally configurable transceivers for the next generation of wireless broadband systems, claims to have launched the world's first reference design for a MicroTCA broadband wireless transceiver. Targeted at small cell WiMAX base station applications — femtocells and picocells — the transceiver has 6 user-selectable channel bandwidths from 1.5 MHz to 14 MHz and can be digitally configured to operate in bands from 2 to 4 GHz.

The re-configurable design supports a variety of network configurations, bandwidths and data rates. This minimizes costs and inventory for wireless system OEMs and operators.

Using a high level command set, the design can be configured for half-duplex and full-duplex operation in both frequency division multiplex (FDM) and time division multiplex (TDM) modes. The board can also be used as a 'plug-and-play' transceiver for rapid evaluation and deployment of WiMAX base stations based upon ACTA or MicroTCA standards.

The zero-IF transceiver uses 12-bit baseband ADCs and DACs. A 40MHz sampling rate is derived from a low-noise clock. Its serial RapidIO interface supports a throughput of up to 3.125 Gbps and can communicate via any advanced mezzanine cards (AMC) ports. A single port carries both I/Q and control traffic and an I/Q record and playback capability simplifies testing. A full speed USB interface is provided for PC controlled standalone operation.

By covering a wide as possible range of interest in terms of bandwidth enables customers to reduce inventory, cut costs and rapidly configure a sytem to changing conditions. The reference design currently spans 2 to 4 GHz bands but the company is looking ahead — for example 700 MHz to 4 GHz.

The reference design is based on a mature second generation SiGe process that is both proven and portable. It can also be ported seamlessly to CMOS.

Some key features of the design include the use of a zero-IF architecture with automated calibration and FPGA-based DSP re-sampling. This not only makes the design adaptable for various sampling rates, but provides designers with a host of FPGA resources to evaluate, diagnose, test and tweak the transceiver.

Lime has been working closely with a number of leading companies in both baseband and RF amplifier technologies. Formal partnership announcements will follow in the next few months, and these agreements will enable Lime to support its customers in the development of complete base stations in which interoperability between the main circuit functions is guaranteed.

Lime is backed by ACT Venture Capital and DFJ Esprit and was founded in March 2005. The company boasts a world class RF design team in the UK that develops IP, backed by a team in Lithuania that implements the IP.

A key on-going goal of the company is to develop 'one-chip' configurable wide-band transceiver solutions while alleviating price pressure dictated by the market.