What does the value of speed grade mean ?

[richardyue]

Hi, members,
What does the value of speed grade mean for the Virtex family devices? For example, the speed grade of XC4VLX15 device in the virtex family is -12, -11 or -10, what does -12 mean? How fast is the speed grade?
Thanks in advance.

 

[echo47]

I don't think the Xilinx "-12" speed grade means anything like 12 MHz or 12 nanoseconds. Its just a code number that you look up in the "switching characteristics" section of the data sheet. There you will find a column of performance values for each speed grade.

 

[Guru59]

Refer to the link given below..................





that is where it is posted....

bye..............

 

[caplash_vlsi]

ok so speed grade means how fast ur fpga can work.....as during the time of fabrcation...some chips are fab. better n some not that good....after all the chips are tested,they r checked for their performance and accord. divided into different groups or speed grades......

 

[haneet]

hi frndz,
acc to what i know there is no sign magnitude for the speed grade. that is just a symbol "dash" used to separate the chip number with the speed grade.
As caplash has mentioned the cause of variation in the speed grade, i would like to add only 1 point that the fabrication is done for one specific speed but after fabrication there is some difference and so these speed grades and based on the speed the chip price is fixed and sold.