# Side of length matching within a differential signal

When we are matching the length of positive and negative tracks of a differential signal in a PCB, is the position of matching important? Does it matter we match the length immediately after the transmitter or the receiver? If yes, which side is preferable and why? It seems there is no discussion about it in the Internet!

I have drown an image to clarify the question:

Edit: The length difference is mainly due to the connection of tracks and pads as shown in this picture:

• The point of running the signal in parallel is not only to match the length but to reduce a common-mode noise, and also keep the same phase on both conductors. So the way you are doing it (with this blip) is not a very good idea. If you have a length difference due to the "right-turn", then equalize it with a "left turn" elsewhere. Commented Feb 22, 2018 at 16:24
• Also, AFAIK you length match after the "unmatching" happens. If you put the extra length close to the transmitter, the signals will be unmatched until the length difference is corrected. Commented Feb 22, 2018 at 16:26
• Actually the length difference is mainly due to connection of tracks and pads. I'm adding an image to the post to clarify this... It should also be noted that I am routing a 10 Gbps signal.
– M.H
Commented Feb 22, 2018 at 16:33
• Then you better approach the pads from a different angle, such as it would perpendicular to the line connecting the two pads. Commented Feb 22, 2018 at 16:41
• @EugeneSh. It's impossible due to other problems...
– M.H
Commented Feb 22, 2018 at 17:08