AR# 22814

14.x Timing Analysis - How do I calculate the flight time for my device?


How can I calculate the trace length/flight time for my device?


For 7 series and newer, partgen gives flight time numbers not delay values.

For pre 7 series devices, you can calculate the trace lengths by running the partgen command. To run the partgen command:

1. Open a DOS command or shell prompt. (note that in 12.x and beyond there is a Xilinx specific command prompt short cut in the accessories folder)
2. Type : partgen -v {part that you need to use} 4vlx25ff668.
3. This creates a dot pkg file with the trace length in microns for each pin in it.

To convert the trace length from microns to flight time:

1. Open the dot pkg file in a text editor. The column on the far right is the trace length in microns.
2.Convert the micron to a millimeter (trace length / 1000).
3. The delay through this is 6.0 - 7.1 ps/mm.

For example:

5610 microns = 5.61 millimeters
5.61 millimeters = 33.66 - 39.83 ps

This is provided only for the Flip-Chip packages. For more information on other parts, see (Xilinx Answer 18078) and (Xilinx Answer 15321).

Improved precision in flight time through package calculation can be found at (Xilinx Answer 34174).
AR# 22814
日期 10/16/2013
状态 Active
Type 综合文章
器件 More Less
Tools More Less