USB 3.2 and Wireless Coexistence
NVIDIA Jetson Xavier NX DG-09693-001_v1.7 | 83
USB SS CONNECTOR PART SELECTION: CHOOSE A BETTER USB 3.2 PART
A USB 3.2 connector has many metal fingers that are perfect in length for radiating in and
around the 2.4 GHz band and beyond. A USB 3.2 connector should be selected to minimize
radiation from the USB 3.2 part itself. Some recommendations are:
Connector fully enclosed by metal
No slots in the connector walls, or if there are slots, the size is very small. Also, the
number of slots should be minimal.
Connector has as many grounding legs as possible. More legs provide better grounding
from the USB 3.2 exterior to the PCB and the structure is less likely to radiate. Choose
four legged connectors over two legged connectors and so on.
The quality of the external USB 3.2 device used in the USB 3.2 port will have impact on the
overall experience. If the external USB 3.2 device used in the USB 3.2 port is of poor quality,
the part itself will radiate and issues will continue. A plastic base USB 3.2 device works
inferior compared to fully metalized USB 3.2 devices.
GROUND THE USB 3.2 PART SOLIDLY
The USB 3.2 connector is grounded through "the grounding legs" previously mentioned. Care
must be taken to ensure the leg area is a very good RF ground. One way to do this is to
increase the number of ground vias placed in the "grounding leg" area.
IMPROVE THE ROUTING AND GROUNDING AROUND THE USB 3.2 PART AREA
The routing and grounding around the USB 3.2 connector part area must be handled carefully.
Since this area is very "hot,” any traces running on the surface layer below the physical
connector part can pick up noise and transfer it to other areas or radiate the noise. These
traces need to be moved to an inner layer, and this area needs to be made a very good ground.
BURY THE USB 3.2 LINES IN INNER LAYERS
The USB 3.2 lines should be routed as impedance controlled differential pairs, with ground on
either side and on the layers above and below.
SHIELD THE USB 3.2 CONNECTOR PART
The radiation from the USB 3.2 connector part is very strong. Need to make a "shield" and put
on top of the USB 3.2 connectors. The shield must touch the USB 3.2 body in multiple points.
The shield track must have number of grounding vias so that any emitted noise from the USB
3.2 connector is swiftly grounded.
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