FEDEVEL
Platform forum

milos.stankovic , 02-09-2020, 05:15 AM

Hi!

I have a question about Advanced PCB Layout Course, Lesson 6. It is about ADD_CMD_CTRL Length Matching. According to L6 video,
these are the signal that are actually length-matched: My questions are:
1. DRAM_RESET_B does not have to be length matched with other signals?
2. I did not find in Activities folder for any lesson that signals are actually length-matched.
Take L7 - 02 - Impedance Adjustment for example.
It is obvious that there are waves on every signal, but yet length ranges from 72.824mm for DRAM_A2 to 85.831 for DRAM_SDCKE0.
Is our task to length match all signals except DRAM_RESET_B within 5 mils?

Best regards,
Milos

robertferanec , 02-11-2020, 02:04 AM

1. RESET is asynchronous (it is not tight up to any timing), it doesn't have to be length matched
2. The routed length will not show you pin to pin length connections - it shows the total length of the signal copper (including the length of ALL branches, not only the branches you need to take into consideration when measuring length between two pins). So this information can not be used for length matching.

milos.stankovic , 02-11-2020, 02:30 AM

Thanks Robert!.

I am aware of routed length and how to length match ADD_CMD_CTRL. It is going to be difficult. To small space.....



Best regards,
Milos