ADD_CMD_CTRL length matching

[milos.stankovic]

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:

DRAM_A0

DRAM_A1

DRAM_A2

DRAM_A3

DRAM_A4

DRAM_A5

DRAM_A6

DRAM_A7

DRAM_A8

DRAM_A9

DRAM_A10

DRAM_A11

DRAM_A12

DRAM_A13

DRAM_A14

DRAM_A15

DRAM_CAS_B

DRAM_RAS_B

DRAM_SDBA0

DRAM_SDBA1

DRAM_SDBA2

DRAM_WE_B

DRAM_CS0_B

DRAM_SDCKE0

DRAM_SDODT0

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]

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]

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