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Adventurer
7,076 Views
Registered: ‎02-08-2016

## Virtex-7 (Logic cells) count versus Virtex Ultrascale (CLB LUTS) - how do I evaluate

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Hi

We build designs with very high logic cell count and interconnect density - but relatively low usage of registers, dsp, block ram etc.

I am using ZC706 which is 85% LUT usage. I want to put a design with approx 4 times more LUTs onto an FPGA.

How does the Virtex-7 200T Logic cell count (1,954,560) stack up against the Virtex Ultrascale XCVU190 CLB LUTs ( 1,074,240 )

Does the Virtex-7 have approx 2 times the logic capacity of the Virtex Ultrascale XCVU190 ?  Or is there a different metric I should use?

Thanks

Simon

1 Solution

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Guide
12,479 Views
Registered: ‎01-23-2009

Forget logic cells...

The LUT and FLOP count for the XCVU190 are correct.

The FLOP count for the V7 2000T is correct.

The LUT count for the V7 2000T is 1,221,600 - this can be calculated as either the FLOP count divided by two, or the "slices" count multiplied by 4 (each slice in 7 series has 4 LUTs and 8 FLOPs)

So, these devices are actually pretty comparable; the 2000T is about 14% larger than the XCVU190.

Avrum

4 Replies
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Professor
7,067 Views
Registered: ‎08-14-2007

Simon,

The Logic Cell count is an arbitrary figure like "system gates."  Its intent is to show a relative measure of logic density using the rough equivalent of one 4-input LUT and one flip-flop.  7-series parts have 6-input LUTs and two flops per LUT.  So the actual LUT count is multiplied by 1.6 to get the "logic cell" count.  Thus the V7 2000T has roughly 1.22M CLB LUTs.  You can also get the CLB LUT count by looking at the "Slices" column, 305,400 for the V7 2000T, and multiply it by 4.

-- Gabor
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Adventurer
7,047 Views
Registered: ‎02-08-2016

Hi Gabor,

Clear as mud  !! I understand these metrics are very rough estimates of usable resources but I still can't make a call between these two devices. I also don't know where you got your numbers from.

from the spec docs of the two parts

XCVU190                      CLB LUTs             1,074,240

CLB FLOPS          2,148,480

Virtex 7 2000T              CLB LUTs              ?

CLB FLOPS           2,443,200

Logic cells              1,954,560

So can you confirm these figures and that the Virtex 7 2000T is approx twice as rich in logic as the XCVU190

Thanks Simon

Highlighted
Guide
12,480 Views
Registered: ‎01-23-2009

Forget logic cells...

The LUT and FLOP count for the XCVU190 are correct.

The FLOP count for the V7 2000T is correct.

The LUT count for the V7 2000T is 1,221,600 - this can be calculated as either the FLOP count divided by two, or the "slices" count multiplied by 4 (each slice in 7 series has 4 LUTs and 8 FLOPs)

So, these devices are actually pretty comparable; the 2000T is about 14% larger than the XCVU190.

Avrum

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Adventurer
7,005 Views
Registered: ‎02-08-2016

Thanks Avrum!

For clarification