Differential signalling help

Question

I am designing a board around the RBp CM3+ and would like to know more about how to wire the camera and USB pins. On the RBp CM3+ data sheet, it is stated that the USB pins like USB_P and USB_M must be routed as 90 Ohm differential traces. I also read somewhere that the camera pins (CAM1_DN0, CAM1_DNP, etc) need to be routed as matched length 100 Ohm differential pairs.

Does this mean that the differential impedance must be around 100 Ohms?

Other than ensuring that the differential traces have the same length and differential impedance, are there any other consideration I should have?

I'm also having trouble understanding the difference between an edge coupled microstrip, microstrips, and embedded microstrips

Answer 1

you may consider this [on-line calculator][1] to get you started (am sure there are many more other good articles explaining this). Yes the differential impedance should be of the order of 100 Ohms. Other considerations, well, try to keep the lengths equal as suggested, and as short as possible, without obstacles or vias changing layers. If its all on the same PCB then you can try keeping the connections as short as possible. If its board-to-board then you'll have more trouble doing that and more carefull consideration to be given. Hope this helps ...

So the main difference between is that the coupled microstrip is differential, the microstrip is the basic transmission line (surface conductor and ground plane), whilst the embedded microstrip is an embedded-into-the-dielectric conductor and a ground plane. Please refer to the right side of the article explaining the different geometries, its all there ... [1]: https://www.eeweb.com/tools/edge-coupled-microstrip-impedance