UniBoard: Xilinx or Altera Eric Kooistra Oude Hoogeveensedijk 4 7990 AA Dwingeloo www.astron.nl Feb 2009 © ASTRON

General comparison Device ranges Device comparison Conclusion Contents Feb 2009 © ASTRON

General comparison Criteria Altera Xilinx Comment Development tools Quartus ISE / EDK Synthesis, softcores Debug tools SignalTap ChipScope Embedded logic analyser MATLAB/ Simulink DSP builder System Generator Generic alternatives: - Synplify DSP - MATLAB HDL coder Softcore μP Nios Microblaze Alternative: - Leon (from Gaisler) Hardcore μP - PowerPC Device ranges Stratix IV Arria II GX Virtex 6 Spartan 6 High end range (40 nm) Low cost range (40 nm) Others experience Bordeaux, Arcetri, Manchester LOFAR, Casper, ASKAP, Nancay, Manchester LOFAR Stratix II  Virtex 4 Keep experience on both A general comparison shows that both Altera and Xilinx offer similar capabilities for FPGA development. Xilinx remarks: PowerPC 440 in Virtex5 (405 in Virtex 4) PicoBlaze softcore for very small control Feb 2009 © ASTRON

Altera - Stratix IV, 40 nm, tx/rx up to 8.5 Gbps Device ranges Altera - Stratix IV, 40 nm, tx/rx up to 8.5 Gbps Xilinx - Virtex 6, 40 nm, tx/rx 3.2, 6.5 Gbps - Virtex 5, 65 nm, tx/rx 3.75, 6.5 Gbps Only consider the newest available FPGAs. Only consider the variants with transceivers. Do not consider older devices: Stratix II, 90 nm, used on LOFAR RSP2, only the GX variant has transceivers (6.375 Gbps) Stratix III, 65 nm, do not have transceivers Virtex 2 Pro, 130 nm, too old, transceivers can only opoerate over at most 3 m copper cable Virtex 4, 90 nm, used on LOFAR RSP3 and TBB, only FX (with powerPC core) has transceiver (6.5 Gbps) Only consider the newest FPGAs and those with transceivers, because: Newest FPGA are closest to Moore’s law and offer most functionality at relatively lowest power (due to smaller nm process) Transceivers are needed for interconnect between FPGAs and for I/O e.g. via 10 GbE Arria and Spartan with transceivers can be interessing lower cost FPGA e.g. for interfacing an ADC to 10 GbE. Altera low cost variants: - Arria II GX, 40 nm, tx/rx at 3.75 Gbps - Arria GX, 90 nm, tx/rx at 3.125 Gbps Xilinx low cost variants: - Spartan 6, 45 nm, tx/rx 3.2 Gbps Altera availability: Stratix IV : EP4SGX230 samples now, others consult factory Arria GX : all buy now Arria II GX : all contact Altera Xilinx availability: Virtex 5 : most buy now Virtex 6 : samples Q2 2009 Spartan 6 : samples Q2 2009 Feb 2009 © ASTRON

Device comparison Criteria Stratix IV Virtex 6 Virtex 5 Comment Device SGX230 SX315T SX240T SX95T Availability Now ? Virtex 6 samples Q2 2009 Price 1000 $ 9000 $ 1700 $ Process 40 nm 65 nm Clock MHz 540 600 550 Multiplier speed Nof transceivers 16 (or 24) 24 16 Virtex: all on one side Stratix: on two sides Nof logic 91200 ALM 49500 slices 37440 slices 14720 1 ALM ≈ 0.6 – 0.9 slices Nof multipliers 1288 1344 1056 640 Virtex: 25x18 Stratix: 18x18 (= 9x9 ?) Block RAM 14.3 Mb 25.3 Mb 18.5 Mb 8.8 Mb Nof IO 560 720 960 Package pins 1152 1759 1738 1136 ETH MAC Soft core 4 Stratix IV has transceiver pins on two sides of the FPGA package, this eases PCB design. The Virtex 5 has all transceiver pins on one side of the package. Stratix IV has devices with up to 48 transceivers. Virtex 6 has relatively more memory and choice between more logic (LXT) instead of DSP (SXT). Nof logic: Xilinx defines a logic cell as 1 4-input LUT + 1 flipflop. For their largest Virtex 5 device the LX330 they state that it has 330 k logic cell and 207360 flipflops which is equivalent to 51.8 k slices. A Virtex 5 slice has 4 6-input LUTs and 4 flipflops. From 330000/(207360/4) it follows that 1 Virtex 5 slice = 6.36 logic elements. Assume that the Virtex 6 slices are equal to the Virtex 5 slices. Hence 315 k logic cells for the Virtex 6 SX315T then corresponds to about 49.5 k slices. Note that 1 Virtex 5 slices is about two Virtex 4 slices, because it has 4 flipflops whereas the Virtex 4 slices has 2 flipflops. One ALM has 2 flipflops. From LOFAR we found that 1 Stratix II ALM is about 1.2 Virtex 4 slices, extrapolating to Stratix IV and Virtex 5 or 6 this would imply that 1 ALM is about 0.6 slice. However Altera claims that 1 ALM is about 0.9 slice on average over a range of different designs. Feb 2009 © ASTRON

Conclusion Both Xilinx or Altera are suitable from FPGA technology and tool point of view. 40 nm for lowest power consumption: - Stratix IV EP4SGX230 is available now - Virtex 6 is expected in Q2 2009 65 nm: Xilinx Virtex 5 are available, but prices for larger FPGA are still high. Both Altera and Xilinx have or will have “low cost” FPGA with transceivers (Xilinx: small Virtex 5, Spartan 6, Altera: Arria GX, Arria II GX) For FPGAs with transceivers Altera Stratix IV has GX and GT (11.2 Gbps) variants, Xilinx has LXT (more logic) and SXT (more mult) variants. For low power 40 nm about 50 % better than 65 nm. Altera reports benchmarks and comparisons of Altera and Xilinx FPGAs and tools, which favour Altera but are not counter acted upon by Xilinx. My feeling is that in general Altera seems to be slightly better at cost, FPGA technology and tools, but not necessarily all the time. Migration from Virtex 5 to Virtex 6 may not be trivial (e.g. board redesign). The future looks OK for both Altera and Xilinx: - 40 nm Stratix IV, Arria II GX - 40 nm Virtex 6, Spartan 6 Feb 2009 © ASTRON