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What Is Better Xilinx VIRTEX 2 Or Altera Stratix ?

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Jun 20, 2001
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SOrry This Subject Sounds Corny, But I'm Intereseted To Know You'r Opinion ?

You must compare the Altera "Stratix" to the Xilinx "Virtex-II-Pro" (not to the "Virtex-II").

The "Virtex-II-Pro" has LOTs (hundreds) of built-in 18x18 Signed Multipliers, and a built-in PowerPC core. The top end 'Virtex-II-Pro' device has 125,136 LEs (Logic Elements) = xxM gates (anybody knows the gates-equivalent number ?) + 556 18-bit Multipliers + 4 x PowerPC processors + 10Mbits RAM + 24 Multi-GigaBits Tranceivers + more. This is a True (almost) SOC device.

The Stratix has its own advantages too - and is not lagging behind at all. The top end Stratix device has - 114,140 LEs (Logic Elements) = xxM gates (again - anybody knows the gates-equivalent number ?) + same RAM (10Mbits) + 229 9-bit Multipliers + LVDS, PCML, LVPECL Tranceivers + DSP processor + NIOS controller and more. Also an almost True SOC device.

Prices ? - Most probably competitive to each other.
Frequency/area Performance - it 'looks' like (from data-sheet) the Xilinx part is better. But no one can REALLY tell - until a practical device was optimized, implemented and tested in Lab.

It looks like the 2 companies are biting each other's "behind" to get the edge - but eventually - they are about even !.

If you refer to Virtex II, and not Virtex II pro, Stratix is better. It’s copper technology, has many enhanced features and for sure it’s faster. I have tried with a really big design and Stratix was around 25-30% faster.

a friend did some quick benchmarks with stratix...he thinks it's not
as good as Virtex's also more expensive. I can't verify this, so
you can just treat it as gossip, but I would tend to beleive him... until
recently he was a big A*tera fan

Couple of comments

I haven't used the stratix device yet, but some comments.
I've found that similar designs end up using less of the FPGA for Xilinx Virtex-II devices and have been able to achieve 120+ MHz synchronous logic for the slowest parts but the Altera Software is much easier and is less buggy than the Xilinx tools.
In terms of cost, I would predict that the Stratix devices will drop quickly in the next year or so. The Virtex II devices were quite pricey but they have experienced a couple of drops in the last year.


IMHO, Virtex II is more powerful end cost effective, then Stratix because of many features, which your can't see at first glance, directly comparing number of LUTs, memories, multipliers, and costs:

- distributed memory of Virtex II makes it possible to built very effective FIR filters (based on the distributed arithmetic), large shift registers, banks of small memories and so on;

- Virtex II block memory size is more appropriate for signal processing (especially for multiple channels), then three block sizes of Stratix (in fact, your can effectively use only one of them);

- besides, Virtex II PRO beats Stratix in terms of silicon recourses.

The only very unpleasant feature in Virtex II (not in Virtex II PRO) for me was a dramatic decrease for speed of embedded multipliers in last Virtex II data sheet some times ago - about 1,5 times! (some my plans were distracted).

But nevertheless, when I regularly choose between Xilinx and Altera products for my projects (for more then 8 years), Xilinx turns out to be the best.


Stratix is fairly new compared with Virtex, it probably will take some time for Stratix to take on major recognition.

I have done some bechmarks as well to compare Stratix vs Virtex II (not Pro). I found they are pretty equivalent for a polyphase FIR filter. However, Stratix became slightly faster when I used the embedded adders inside the DSP blocs. The DSP block makes the Stratix best suited than Virtex II for FIR applications: free adders, shift registers for the taps, ...

The big amount of 512-bit RAM in Stratix compensate easily for the distributed RAM inside Xilinx part. Virtex II 18k-bit RAM was cool for my previous design, but in my last, the mega 512k-bit megablocks were very cool and there were less memory loss with the big amount of 4k-bit RAMs.

However, for the price/logic/multiplier, there are more multipliers in Virtex II than Stratix for the same amount of logic cells (not gate).

I already said that: Altera and Xilinx will never lose a sale to their competitor because of price!!!

Tools? Quartus II v2.3 crashed 3 times today! ISE5.1 works only on XP or 2000. Debugging tools (signal tap & chip scope) look similar.

My opinion: ex equo! Very hard to choose between the two! It really depends on the application.

Here's the Altera claims (I talked to one of their guy yesterday):

- Stratix is potentially faster than VirtexII because all layers are copper instead of just the power layers

- Altera has better price margins on Stratix than Xilinx because the technology is 0.13u instead of 0.15u (hum! numbers are correct?)

They think it will be the big winner in 2003!

Stratix does have more features than Virtex-II.
It has better DSP blocks, bigger memories, 3 types of memories.
It is lacking only the front high speed SERDES and hardcore embedded CPU compare to Virtex-II pro.
Virtex-II is 0.13 process if I am not mistaken.
Virtex-II clocking architecture is limited in sense if you have high number of global clock usage dues to it's BUFGMUX limitations.

Stratix got more global clock resources and have very flexible PLLs.
The price for Stratix is very competitive.

There will be another version of Stratix with Embedded CPU and high speed SERDES coming this year.

This competition between A & X is very good for us FPGA designers.

The new device Stratix G series have front high speed SERDES. The Stratix's
differential pairs surport more standard but its pin is not flexible than Virtix-II, its
differential pairs are fixed as input or outputcan, and Virtex-II's differential pairs can be programmed as input or output.

You shall probably need some support from the vendor and, I think Xilinx support is better.

It is depended on your application case. If you tell me your application i recommend you a good fpga?

Altera often said before they do.
xilinx often do before they said.
I have seen the stratix GX demo board .It just a stratix chip + serdes chip.

hi i think that if you need to have a secure bitstream virtex II is betther.
he have a triple des core encription that is a good resource.


What Is Better Xilinx VIRTEX 2 Or @ltera Stratix ?

I have implemented a design on both ViretxII and startix10F. The area utilization in Virtex was much better than Stratix. I don't know that it returns to better synthesis / p&r by Xilinx tools or to the FPGA structure.

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