Hi,

I am designing a PCB and having issue with the impedance matching of the differential pair. I am using the guidelines of the IC manufacture to design my PCB. Here is the link of:

According to this guidelines, the differential pair (DP and DM signals of the USB) must have 90 ohm impedance to each other. But I am not able to match this impedance. I tried using different line width (10mils,15mils,20mils,25mils,30mils) of the differential pair but it doesn’t help me. Also, I tried using 0 ohm resistor in between that didn’t help as well.

The specifications of my PCB are- the conductor thickness is 2oz(2.8mils) and the dielectric thickness is 63 mils (using FR-4 and dielectric constant is 4.5).

Can anyone please help me in resolving this issue ??

Thanks