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The synergy between FPGAs and optical interconnect for applications beyond networking and telecom

by Xilinx Employee on ‎06-25-2014 03:26 PM (59,150 Views)

Two articles in the May issue of RTC Magazine highlight the synergy between FPGAs and optical interconnect—for applications beyond networking and telecom. The first article, “VPX Optical Interfaces Boost System Capabilities” written by Roger Hosking of Pentek, discusses the use of optical modules to drive suitably equipped VPX system backplanes and focuses on Pentek’s Model 5973 VPX FPM Carrier based on a Xilinx Virtex-7 FPGA. Here’s a photo:



Pentek Model 5973 VPX Virtex-7 FMC Carrier.jpg 


Pentek Model 5973 VPX FPM Carrier based on a Xilinx Virtex-7 FPGA



Hosking writes, “For well over 150 years, copper interconnections have served the telecommunication and radio industry admirably for nearly all implementations of industrial, commercial, military and consumer products. However, over the last 15 years, optical interconnections have advanced rapidly to meet exploding market demands for telcom, data servers, storage facilities and the Internet infrastructure. Optical links offer many advantages over copper that are critical for these applications.”


Later in the article, Hosking describes the optical aspects of the Pentek Model 5973 VPX FPM Carrier card, “This Virtex-7-based 3U VPX carrier for FMC modules connects the (optical) Samtec Firefly modules directly to the Xilinx GTX gigabit serial I/O pins, supporting a variety of FPGA-based protocols. The product eliminates the cumbersome front panel connectors, simplifies installation and maintenance, and reduces system complexity. VITA 66.4 complements the standard PCIe Gen 3 x8 copper interface with a full duplex, multi-mode fiber link delivering more than 10 Gbytes/s of I/O to other systems, racks or sensors located at distances of 100 meters or more.”


The second May RTC Magazine article, “New System Architectures to Interface High Data Rate Sensors” written by Thierry Wastiaux of Interface concept, discusses his company’s IC-QSFP-FMCa mezzanine card with two QFSP+ optical interfaces. Wastiaux writes, “Delivering high-frequency signals through long coaxial cables from the sensor to the processing units has a number of disadvantages. Even the last generation of high-definition IR and daylight optical sensors or RF antenna systems generated a tremendous flow of sample data feeding the processing units, and with the high frequency the signal loss can be high. In addition, copper cables carrying these analog high-frequency signals present EMI radiation and susceptibility issues.”


The solution, again, is optical interconnect. Wastiaux’s article continues, “The IC-QSFP-FMCa can be seen as a good example of an optical interface in a small form factor. This VITA 57 FMC features two QSFP cages, each of which is able to receive a four-fiber optical QSFP+ interface. Each of these QSFP+ interfaces allows communication on four full-duplex lanes at a data rate up to 10 Gbit/s per lane, depending on the maximum data rate achievable on the FPGA transceiver interface. They can reach a distance of up to 100 meters with multimode 850 nm fiber. A total of eight SERDES run up to the FMC connector to interface the signal processing module.”


Here’s a block diagram of the OpenVPX system based on a Xilinx Virtex-7 FPGA that Wastiaux describes in his article:



Interface Concept OpenVPX system block diagram.jpg


Interface Concept OpenVPX system with optical interconnect based on a Xilinx Virtex-7 FPGA



Wastiaux writes, “The relevant IPs in the FPGA (FFT, Beamforming, filtering, down conversion among others) process the data samples received through the optical interfaces using the great resources of the Virtex-7 especially in terms of DSP logic elements. The processing results may be stored in the two high-bandwidth DDR3 banks, each of which has a 64-bit interface. These 2Gbyte memory banks allow the storage of a large amount of data before transfer to other part of the system.”


Finally, here’s a photo of the Interface Concept mezzanine board with two QSFP+ optical ports:



Interface Concept IC-QSFP-FMCa mezzanine card.jpg

Interface Concept IC-QSFP-FMCa mezzanine board with two QFSP+ optical ports





For more information on the Pentek Model 5973 VPX FPM Carrier, see:


Pentek OpenVPX board points the way to multi-Gbps optical backplanes using VITA 66.4 optical interconnect




For more information on the Samtec Firefly optical modules, see:


Samtec FireFly multi-Gbps interconnect system lets you choose between photons (100M) and electrons (28Gbps/channel)


More about the Samtec FireFly multi-Gbps optical interconnect system for high-speed backplanes in FPGA-based systems