What is the main difference between Spartan-3 and Virtex-4 FPGA?

[buenos]

hi.

what is the main difference between a spartan-3 and a Virtex-4 FPGA?
If i select 1-1 of them with the same number of CLBs, then why the virtex is much more expensive?
because of the PowerPC cores? or is the virtex more effective? faster?
And what about Power consumption?

 

[banjo]

spartan or virtex

Spartan-3 devices usually have fewer BlockRams, fewer DCMs, and fewer routing channels. They also are not quite as fast. It is pretty common to design first on the Virtex and then try to cost reduce into a Spartan.

Every feature that you do not use in the FPGA is wasted. If you only use 20 of 30 available BlockRams, then scaling back to a smaller part or a Spartan can reduce the cost of the entire assembly.

Generally, the Spartans are lower power because they run slower and have less stuff in them.

Be careful with the Xilinx sales literature, their comparison tables sometimes leave out the areas with the biggest differences.

 

[buenos]

spartan or virtex

thank you.

some more questions:
As i know the fastest signals on a spartan can be about up to 300MHz. But when someone implements something, then it can run up to Fmax, where Fmax<<300MHz.
How is it on the virtex devices? The realation between the FPGA Fmax and implemented design Fmax, is the same? Or better? What is the Fmax of the Virtex-2/4/5? If you implement a Microblaze, what is the max speed usually? We used Microblaze at 50MHz on Spartan-3.

What about Gbps serial interfaces, like PCIe? do they work on both families? how? IOBs are faster on Virtex? IOBs are faster than CLBs in this case?

 

[my_garden]

spartan or virtex

Virtex's Fmax is much higher than Spartan series.
Virtex's primary clock can reach 550Mhz; spartan3's primay clock is only 306Mhz.
And virtex has more routing resource and different LUT architecture(Virtex5 LUT6), so after logic P&R. Virtex will much faster than Spartan.

And only Virtex series has SERDES for PCI express. If you hope Spartan3 to support PCI express, you should add one extend SERDES asic.

 

[buenos]

spartan or virtex

thanx
thats what i wanted to know.