#6 input lut upgrade#
#6 input lut series#

In older Virtex and Spartan technologies, even though the LUT was a 4-input LUT, Xilinx used the figure 1.25 logic cells per LUT/FF pair in the CLB.

#6 input lut upgrade#

I suggest you choose your vendor, port enough of your design to get an idea of how big a FPGA you need and choose a FPGA with an upgrade path (if you want to market). the actual number of LUT inputs (the newer Xilinx families all use 6 input LUTs) - additional combinatorial logic that exists in the FPGA fabric (outside the actual LUT). The same design on two different foundries should have similar system gates number, as waste is not really an issue for ASIC. System gates is a common measure of ASIC design complexity. Same with fast-carry logic, I don't know if they count that in equivalent gate number, but be advised that number is inflated. But given 2-inputs, there’s lots of possible output combinations, which all must be possible to satisfy given a 2-input LUT. The above examples show a 2-input LUT that has been configured to be an AND gate and an OR gate. A Xilinx FPGA should fit 1.5 times the logic of an Altera FPGA, since it's LUT have 6 instead of 4, right? Well, it largely depends on the design, if the design can't use 6-inputs much, the unused ones are wasted. A Look-Up Table (LUT) is how any arbitrary Boolean logic gets implemented inside your FPGA. They are aggregated in logic blocks which has other features like fast-carry chain, registers and distributed memory.Ĭonverting to system gates is useful, but don't forget it's also a marketing war. 6-input LUT structure: a configurable logic block contains two slices.

#6 input lut series#

In their most recent architecture, Xilinx use 6-input LUT and altera 4-input LUT. Virtex 7 series FPGAs and Virtex 6 FPGAs have employed the. 46 Detailed schematic of a standard fracturable 6-input LUT. Xilinx use LUT, Altera LE, microsemi/lattice possibly something else. 46 illustrates the detailed schematic of a standard fracturable 6-input LUT, where the 5th and 6th inputs can be pull up/down to a fixed logic value to enable LUT4 and LUT5 outputs.

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