The gigabit serial interfaces of the FX were organized into two groups of four bi-directional serial bit lanes to form two 4X ports. Supported by the internal 8B10B channel coding circuitry, these ports form the physical and transport layers of XMC standard. IP cores can be installed to implement specific switched fabric standards including SerialRapidIO, PCI Express and others. Operating at bit clock rates up to 3.125 GHz, these I/O facilities eliminate many of the data flow bottlenecks that frequently plague real-time software radio systems.

Two high-speed parallel data buses join the two FPGAs. The 64-bit local bus supports traffic to and from the PCI interface sustaining rates up to 133 MHz. Three 32-bit buses use source synchronous digital interfaces for moving data between them at up to 600 MHz to support the full 2.5 GByte/sec streaming transfer rate of the XMC ports.

Judicious choices of Virtex-4 sub-family members to meet specific needs of the hardware and target applications satisfied all of the product design objectives. An additional bonus arises from the “footprint” consistency between certain members of different Virtex-4 sub-families. Since the SX55 and the LX100 share a common printed circuit board pattern, or footprint, this module can be assembled with either device. For applications requiring maximum amount of logic resources, simply replacing the SX55 with the LX100 device can double the number of logic slices.

Summary

As software radio technology drives an increasingly diverse array of commercial, industrial, military and government electronic systems, the new features and inherent flexibility afforded by FPGAs deliver an excellent solution. A wealth of IP core offerings for highly-optimized algorithms, interfaces, and protocols help COTS board vendors shorten their time to market, and help systems integrators add critical functions to these FPGA-based COTS products for specialized turnkey applications. Each new FPGA generation promises both a higher density of existing resources and the emergence of new types of resources to add even more performance to embedded software radio systems.

This article was written by Rodger Hosking, Vice President and co-founder of Pentek, Inc. (Upper Saddle River, NJ). For more information, contact Mr. Hosking at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it , or click here.