•  
• EDN Europe MAGAZINE
•  
• Free SUBSCRIPTION
• Subscription Renewal
• View Media Kit

• EDN
• EDN Australia
• EDN Asia
• EDN China
• EDN Japan

BROADBAND-TRANSCEIVER-CHIP MAKER TARGETS WiMAX BASE-STATION SOCKETS

Lime Microsystems is a fabless semiconductor start-up based in the UK that has been developing transceiver technology for use with wireless standards such as WiMax. The company has announced a reference design for a MicroTCA-format card hosting a transceiver (employing its own IP) that it aims at the “femto” and “pico” cell level of WiMax base stations. The design has six selectable channel bandwidths from 1.5 to 14 MHz and is digitally configurable to operate from 2 to 4 GHz. The feature set of the
TCA design is configurable to broaden its appeal to system OEMs, who can use the board to evaluate WiMax services; it supports half- or full-duplex operation in FDM or TDM modes. Lime says that its potential customers are already users of the TCA format for development, and the company believes that TCA will “find its way to the edge of the network in low-cost form factors.” Lime envisages a base-station bill-of-materials of around $100, of which the baseband silicon would account for 20% and the RF silicon, 7 to 8%.

Lime’s core technology is concerned with building the RF transceiver on CMOS. First silicon does, in fact, use SiGe technology, but the architecture will readily port to pure CMOS, the company believes. Lime designed the IP for broadband operation and wide channel bandwidth—the first application is WiMax, but the technology is potentially more widely applicable. In concept, say Lime’s founders, the design is a “structurally typical”, zero-IF transceiver, its unique properties residing in the basic building blocks and algorithms the company uses, which leads to high integration and a single transceiver for multiple frequencies. The design uses 12-bit ADCs and DACs sampling at 40 MHz; Lime’s designers have not integrated the converters in their first design release but will do so in a later product. Similarly, this version is a single-channel device, and the multiple signal paths needed to support MIMO operation will also follow later in 2008.

The first release of the µTCA board, using a two-chip transceiver implementation, a Freescale MCF52223 microcontroller, and an Altera Stratix II GX FPGA, costs $12,000. The FPGA carries out re-configurable DSP re-sampling and has spare capacity for developers to add their own DSP code.

Lime Microsystems, www.limemicro.com.