Should I consider my design as Stripline in USB differential pair impedance calculation?

Thread Starter

sfcircuit

Joined Jan 26, 2018
2
Hi,

I am designing a PCB of project that involves USB 2.0 differential pair trace. It is a 4-layer board with the following configuration:

Top layer: Analog and low-speed digital signal
Layer 2: 3.0V Power plane
Layer 1: USB2.0 Differential pair trace
Bottom layer: Ground plane

Also shown in the following figure.


I am planning to use Saturn PCB to calculate the impedance of the USB 2.0 differential pair, as shown below.



However, I am not sure whether should I use symmetric stripline impedance for the impedance calculation, because according to this:

http://www.bitweenie.com/listings/microstrip-vs-stripline/

for a stripline, the transmission line is in between of 2 ground planes, however in my design, the transmission line is in between of a power plane and a ground plane.

There are a few more choices for the calculation provided by Saturn PCB Toolkit as shown below.


I would like to know which one should I select for the USB 2.0 differential pair impedance calculation.

Thank you.
 

Attachments

andrewmm

Joined Feb 25, 2011
249
people tend to use micro strip for the USB 2.0, on the top layer.

The transceivers tend to be pinned out for that .

Tip, keep the tracks short,
 
Top