USB 3.0 coupling capacitor placement

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

The Jetson implementation guide mentions the requirement for 2 sets of ac coupling capacitors on both the SSRX and SSTX pairs when connecting between the TX2 SOM and an on-board USB device.

Our application has a USB hub co-located on the same board as the Jetson TX2. the question I have is where are the AC coupling capacitors placed when making the upstream connection?

[SOM RX+]–||-------------[HUB TX+]
[SOM RX-]–||-------------[HUB TX-]
0.1uF

[SOM TX+]-------------||–[HUB RX+]
[SOM TX-]-------------||–[HUB RX-]
0.1uF

Thanks,

Steve.

2

Yes as your design, the AC cap location should be located as close as possible to nearby discontinuities.

3

The only discontiuity (Unless the USB hub device package is counted as a discontinuity), is the Samtec SEAF socket for the TX2 SOM. Should all 4 capacitors (2 on the sstx signals and 2 on the ssrx signals) be located as close as possible to the TX2 connector, or is there a more favored placement?

Thanks,

Steve

4

If that’s the only discontinuity, then all caps should be close to it.