USB, PCIe, and UFS
Jetson AGX Xavier Series Product DG-09840-001_v2.5 | 44
Parameter Requirement Units Notes
Time-domain Reflectometer (TDR) Dip
GEN1
GEN2
75
75
Ω
@ Tr = 200ps (10%-90%)
@ Tr = 61ps (10%-90%)
Near End Crosstalk (NEXT) ≤ −45 dB DC – 5GHz per each TX-RX NEXT
GEN1 IL/NEXT plot
GEN2 IL/NEXT plot
Trace Impedance: Diff pair / Single Ended 85 / 43 Ω
±15%. Intrinsic Zdf, does not account for
coupling from other trace pairs
Reference plane GND
Trace loss characteristic:
GEN1
GEN2
< 0.7
< 0.9
dB/in
@ 2.5GHz
@ 5GHz
• The following max length is derived based on the trace loss characteristic above. The length constraint must be re-defined if loss characteristic is
changed.
• The trace loss profile for Gen2 support is based on the dielectric material EM370(5). See the loss plots in the sheet "USB3 LOSS BUDGET"
•
Note that microstrip loss could be similar to stripline due to humidity effect
Breakout Region – Max length 11 mm Minimum trace width and spacing
Max Trace Length
GEN1 Host
GEN1 Device
GEN2 Host or Device
152 (1014)
50.8 (234)
127 (850)
mm (ps)
Stripline (6.7ps/mm) assumed
Max Intra-Pair Skew (RX/TX_N to RX/TX_P) 0.15 (1) mm (ps)
Do not perform length matching within
breakout region. Trace length matching
should be done before discontinuities. See
Note 2
Differential pair uncoupled length 6.29 (41.9) mm (ps)
Trace Spacing for TX/RX Non-
Interleaving
TX-RX Xtalk is very critical in PCB trace routing. The ideal solution is to route TX and RX on different layers.
If routing on the same layer, strongly recommend not interleaving TX and RX lanes
If have to have interleaving routing in breakout, all the inter-pair spacing should follow the rule of inter-SNEXT (between TX/RX pair
spacing)
The breakout trace width is suggested to be the minimum to increase inter-pair spacing
Do not perform serpentine routing for intra-pair skew compensation in the breakout region
Min Inter-SNEXT (between TX/RX)
Breakout
4.85x
This is the recommended dimensions for
meeting the NEXT requirement.
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